Normal Operation Period Research Articles

Biodegradable and flexible ι-carrageenan based RRAM with ultralow power consumption

Transient memories, which can physically disappear without leaving traceable remains over a period of normal operation, are attracting increasing attention for potential applications in the fields of data security and green electronics. Resistive random access memory (RRAM) is a promising candidate for next-generation memory. In this context, biocompatible ι-carrageenan (ι-car), extracted from natural seaweed, is introduced for the fabrication of RRAM devices (Ag/ι-car/Pt). Taking advantage of the complexation processes between the functional groups (C–O–C, C–O–H, et al.) and Ag metal ions, a lower migration barrier of Ag ions and a high-speed switching (22.2 ns for SET operation/26 ns for RESET operation) were achieved, resulting in an ultralow power consumption of 56 fJ. And the prepared Ag/ι-car/Pt RRAM devices also revealed the capacities of multilevel storage and flexibility. In addition, thanks to the hydrophilic groups of ι-car molecule, the RRAM devices can be rapidly dissolved in deionized (DI) water within 13 minutes, showing excellent transient characteristics. This work demonstrates that ι-car based RRAM devices have great potential for applications in secure storage applications, flexible electronics and transient electronics.

Effects of programmed maintenance shutdowns on effluent quality of a bleached kraft pulp mill

Abstract Routinely, the mills perform programmed maintenance shutdowns (PMS) that can affect the characteristics of the effluents and the performance of the effluent treatment plant (ETP). A careful planning of the PMS, along with the use of industrial process sectorial spill control and the use of the emergency spill lagoon have considerably minimized these effects. The Suzano pulp mill located in Aracruz (Brazil) has three production lines and carry out, on average, PMS of each production line separately, every 15 months of operation. The purpose of the study was to evaluate the effects of the PMS on the effluent characteristics and performance of the ETP compared to the periods of normal operation. The results showed that during the PMS, the physicochemical characteristics of the raw and treated effluents were like those found during normal operation. The lower organic loads found in the effluents during the PMS periods were associated with the decrease of the flow rates and the increase of the hydraulic retention time of the ETP, causing a better performance of COD, BOD, TSS and AOX removal. A proper planning of the PMS improved the performance of the ETP and the treated effluent quality remained similar to those during the normal operating period.

PROBABILISTIC FORECASTING OF THE SERVICE LIFE OF REINFORCED CONCRETE AT ARCTIC OIL AND GAS FACILITIES, CONSIDERING DEFECTS AND DAMAGE

Currently, large fuel and energy companies are conducting intensive development of the Arctic territories of the Russian Federation by commissioning new capital construction facilities. At the same time, new formulations of modified concrete with improved performance properties are used. However, in extreme construction conditions, defects and damages can form, which affect the durability of structures. The paper presents the results of probabilistic modeling of the failure-free operation of reinforced concrete according to the criterion of the impact of carbon dioxide on concrete for the conditions of the new shift settlement Sabetta. Concretes with a water-cement ratio of 0.35 and 0.5 on slag-Portland cement were taken as calculated values. The results showed that without defects and damage, the period of normal operation generally corresponds to the design value of 50 and 100 years. If there are defects, the first local areas will appear in 40 years. Recommendations on repair of the considered defects and damages are given.

ІНФОРМАЦІЙНІ ТЕХНОЛОГІЇ В ОЦІНЦІ ТЕХНІЧНИХ ХАРАКТЕРИСТИК ЖИТЛОВИХ БУДІВЕЛЬ

Abstract Literary sources have been elaborated, which reveal the main topics of the discussed questions regarding the implementation of safe operation and due to which it is possible to increase the life span of buildings or structures. Literary sources on the implementation and implementation of ВIM technologies on the territory of Ukraine, ensuring reliable maintenance of buildings during the period of operation have been elaborated. Familiarity with the capabilities of application software for information control and support during all stages of the life cycle to preserve the durability of the building was conducted. Data on the period of normal operation of some of the structural elements (sewer pipes, water pipes, etc.) were processed for maintenance or replacement planning. The main factors in the operation of buildings and structures are considered: climatic characteristics, location, load and influences, which in turn have a direct impact on the service life and technical characteristics, as well as the number and frequency of planned works or repairs to maintain the normal technical condition of the building . Work was carried out on the analysis of existing practices for assessing the technical characteristics of buildings and structures, estimated determinations of residual operational resources, technical characteristics and periods of trouble-free operation. Inspection and assessment of the technical condition, causes of problems and detection of defects, announcement of possible remedial measures. It has been analyzed how important digital information is and the presentation of such data in a centralized system. One database will greatly facilitate the processes of information collection, speed up support during maintenance. All processes will improve thanks to the ability to quickly receive the necessary information for further analysis and monitoring of the object's functioning, decision-making, planning, etc. The advantages and disadvantages of the approaches were studied and a conclusion was drawn.

Research on Influencing Factors of Traffic Conflicts in Freeway Diverging Area during the Maintenance Period

Based on the traffic conflict techniques, a microscopic safety analysis framework is presented to study traffic conflicts in the freeway exit ramp diverging area (FERDA) during the maintenance period. A manual–software combination data processing approach was used to extract trajectory data from aerial videos and identify actual conflicts. Simulation conflicts were obtained from the VISSIM simulation model. Firstly, the conflict features of maintenance and normal operation periods were compared. Subsequently, conflicts were classified as lane-change conflicts or rear-end conflicts to investigate their spatiotemporal characteristics during the maintenance period. Finally, a random parameters multinomial logit model was developed to study the influencing factors and heterogeneity of conflicts. The results revealed that the FERDA has a higher collision risk during the maintenance period compared with the normal operation period. Additionally, lane-change conflicts have a higher occurrence probability than rear-end conflicts, but a shorter duration. Besides, the conflict density heat map showed that the lane-change conflicts and rear-end conflicts are densely distributed at 0–150 m and the middle lane of the FERDA, respectively. The model results indicated that the factors that significantly influence conflicts include velocity, acceleration, type, position, and destination of vehicle, the heavy vehicle percentage, total number of vehicles in the FERDA, and the velocity and destination difference between vehicles. Among these factors, the type of vehicle, destination difference, and the position of vehicles (at 150–270 m of the FERDA) were found that have significantly heterogeneous impacts on the two types of conflicts. This study is expected to provide safety analysts with an effective analysis method for evaluating the risk of the FERDA during the maintenance period. Additionally, the concluded influencing factors can potentially help develop different and effective safety countermeasures for different types of conflicts.

Subsidiary closures and relocations in the multinational enterprise: Reinstating cooperation in subsidiaries to enable knowledge transfer

Subsidiary closures and relocations, a process whereby a multinational enterprise (MNE) closes down a subsidiary and relocates its activities, are commonplace and increasing. Yet we lack an understanding of how knowledge in such situations can be successfully transferred to prevent loss and provide for future knowledge recombination in the MNE. Compared to periods of normal operation, knowledge sharing during subsidiary relocations is likely compromised by diminished sender motivation. In a detailed case study of a subsidiary closure and relocation, we find that the announcement of a subsidiary closure can lead to a break in cooperative behavior that inhibits knowledge transfer. It is therefore critical to reinstate cooperative behavior among subsidiary employees. Reinstatement can be achieved through a set of subsidiary leadership practices that affect the emotions of employees and subsidiary identity. This finding contributes to our understanding of knowledge transfer dynamics in MNEs during subsidiary relocations and closures, extends theory on the practices of subsidiary leadership in subsidiary death and adds to our understanding of identity in MNEs.

ОПРЕДЕЛЕНИЕ НАДЕЖНОСТИ ЭЛЕМЕНТОВ ГАЗОПОРШНЕВЫХ АГРЕГАТОВ С СИНХРОННЫМИ ГЕНЕРАТОРАМИ МЕТОДОМ АНАЛИЗА ИЕРАРХИЙ

Relevance In the process of extracting hydrocarbon raw materials, associated petroleum gas (APG) is released, which in itself is a valuable fuel. Previously, associated gas released during extraction was simply burned, which was irrational and harmful to the environment. However, in modern conditions, oil companies tend to use associated gas. One of the best available technologies for the utilization of associated petroleum gas and the generation of electric energy is the use of gas piston units (GPU) at oil and gas producing enterprises, which are widely used at the present time. Progress in design methods and production technology of electric machines is expressed, among other things, in increasing their reliability, however, it is obvious that it will not be possible to completely avoid failures. The problem of solving issues of assessing and ensuring the reliability of GPU used for the utilization of associated petroleum gas at oil-producing enterprises is becoming more and more urgent every year, since serious losses of an economic and environmental nature are associated with insufficient reliability: emergency stops of GPU lead to the shutdown of funds of oil-producing wells and forced burning of APG on an open-type candle with the release of a large amount of the amount of greenhouse gases. Aim of research To study the reliability of gas piston units based on the weight indicators of their elements (functional units). Research methods The research uses the hierarchy analysis method (Saaty method) and the «weakest link» method. Results The article uses a methodology for evaluating equipment reliability indicators based on the weight indicators of functional units, taking into account the importance of reliability criteria. The node weight is calculated using the hierarchy analysis method (Saaty method). In accordance with the proposed methodology, the probability of trouble-free operation of the considered machines for the period of normal operation is calculated. Conclusions are drawn about the prioritization of technical impact on functional elements.

Impacts of TROPOMI-Derived NO X Emissions on NO2 and O3 Simulations in the NCP during COVID-19.

NO2 and O3 simulations have great uncertainties during the COVID-19 epidemic, but their biases and spatial distributions can be improved with NO2 assimilations. This study adopted two top-down NO X inversions and estimated their impacts on NO2 and O3 simulation for three periods: the normal operation period (P1), the epidemic lockdown period following the Spring Festival (P2), and back to work period (P3) in the North China Plain (NCP). Two TROPOspheric Monitoring Instrument (TROPOMI) NO2 retrievals came from the Royal Netherlands Meteorological Institute (KNMI) and the University of Science and Technology of China (USTC), respectively. Compared to the prior NO X emissions, the two TROPOMI posteriors greatly reduced the biases between simulations with in situ measurements (NO2 MREs: prior 85%, KNMI -27%, USTC -15%; O3 MREs: Prior -39%, KNMI 18%, USTC 11%). The NO X budgets from the USTC posterior were 17-31% higher than those from the KNMI one. Consequently, surface NO2 levels constrained by USTC-TROPOMI were 9-20% higher than those by the KNMI one, and O3 is 6-12% lower. Moreover, USTC posterior simulations showed more significant changes in adjacent periods (surface NO2: P2 vs P1, -46%, P3 vs P2, +25%; surface O3: P2 vs P1, +75%, P3 vs P2, +18%) than the KNMI one. For the transport flux in Beijing (BJ), the O3 flux differed by 5-6% between the two posteriori simulations, but the difference of NO2 flux between P2 and P3 was significant, where the USTC posterior NO2 flux was 1.5-2 times higher than the KNMI one. Overall, our results highlight the discrepancies in NO2 and O3 simulations constrained by two TROPOMI products and demonstrate that the USTC posterior has lower bias in the NCP during COVD-19.

A STUDY ON THE CONTINUOUS USAGE OF ORGANIC,INORGANIC PERSISTENT PESTICIDES IN THE AGRICULTURALFIELDS IN AND AROUND SIRUMALAI AREA WITH A SPECIALREFERENCE TO THE IMPACT ON GROUND WATER AND SOIL

In the present study the impact of pesticide pollution due to the discharge of pesticide waste water from the agricultural field in the Sirumalai agro lands was studied. In order to evaluate the physical and chemical parameters of water, the pond water samples, and the ground water samplesall the sides were collected and analyzed for various water quality parameters and soil parameters. The pond water is the main source of water for the bore wells located in and around the agricultural land. During the rainy season the pond water percolates into wells and bore wells. Now water is completely polluted due to percolation of pesticide waste waters which are potentially harmful, accumulation of various pesticides chemical residues in water reaches the ground water source. Bio – accumulation and bio-concentration of the pesticide waste water causes high degree of pollution. The bore wells in and around the northern side of the pond polluted with very high TDS and it is beyond redemption due to the higher limits of TDS, hardness, phosphate, ammonia and nitrate. All the water samples taken in and around the agriland are notchemically portable. The presence study reveals that the physico-chemical analysis of pond water in the pond as well as ground waters are above the permissible limit. The dissolved oxygen is analyzed and found to be deteriorated. It is due to utilization of dissolved oxygen in the water byorganic matter and by the pesticides. The investigator observed that the solar evaporation tank made of black body tank, function more effectively during summer with very high evaporationrate. The investigator found that during the normal operation period, the colour of the effluent varies and becomes clear after treatment with alum, which favours the penetration of solar energy easily and hence the efficiency of the evaporation tank increases than the normal cement slab. The advantage of utilizing the black body natural kadappa tanks for evaporation is very strong and it can absorb very high degree of solar radiation which is converted into thermal energy. The investigator observed that the solar evaporation tank made of black body tank function more effectively during summer with very high evaporation rate. The solar evaporation tank is blessed in principle of black body surface which can absorb solar radiation more effectively than ordinary cement slab.

Estimation of Temporal Variation of Discharged Tritium from Port of Fukushima Dai-ichi Nuclear Power Plant: Analysis of the Temporal Variation and Comparison with released Tritium from Japan and Major Nuclear Facilities Worldwide

We estimate the monthly discharge inventory of tritium from the port of Fukushima Daiichi Nuclear Power Plant (1F) from Jun. 2013 to Mar. 2020 using the Voronoi tessellation scheme, following the tritium monitoring inside the port that started in Jun. 2013. As for the missing period from the initial month, Apr. 2011 to May 2013, we calculate the tritium discharge by utilizing the ratio of tritium concentration to 137Cs concentration in stagnant contaminant water during the initial direct run-off period to Jun. 2011 and the discharge inventory correlation between tritium and 137Cs for the next-unknown continuous-discharge period up to May 2013. From all the estimated results over 9 years, we found that the monthly discharge inventory sharply dropped immediately after closing the seaside impermeable wall in Oct. 2015 and subsequently coincided well with the sum of those of drainage and subdrain etc. By comparing the estimated results with those in the normal operation period before the accident, we point out that the discharge inventory from the 1F port after the accident is not very large. Even the estimation for the year 2011 is found to be comparable to the maximum of operating pressurized water reactors releasing relatively large inventories in the number of digits. In the national level, the total domestic release inventory in Japan significantly decreased after the accident owing to the operational shutdown of most plants. Furthermore, 1F and even the total Japanese discharge inventory are found to be minor compared with those of nuclear reprocessing plants and heavy-water reactors on a worldwide level. From the above, we suggest that various scenarios can be openly discussed regarding the management of tritium stored inside 1F with the help of the present estimated data and its comparison with the past discharge inventory.

Pumping Station Design in Water Distribution Networks Considering the Optimal Flow Distribution between Sources and Capital and Operating Costs

The investment and operating costs of pumping stations in drinking water distribution networks are some of the highest public costs in urban sectors. Generally, these systems are designed based on extreme scenarios. However, in periods of normal operation, extra energy is produced, thereby generating excess costs. To avoid this problem, this work presents a new methodology for the design of pumping stations. The proposed technique is based on the use of a setpoint curve to optimize the operating and investment costs of a station simultaneously. According to this purpose, a novel mathematical optimization model is developed. The solution output by the model includes the selection of the pumps, the dimensions of pipelines, and the optimal flow distribution among all water sources for a given network. To demonstrate the advantages of using this technique, a case study network is presented. A pseudo-genetic algorithm (PGA) is implemented to resolve the optimization model. Finally, the obtained results show that it is possible to determine the full design and operating conditions required to achieve the lowest cost in a multiple pump station network.

Evaluating the effect of considering repairing-fault periods on calculating technical losses in medium-voltage feeders of ring distribution networks

Energy losses represent one of the main challenges for electric power distribution utilities all over the world. Several papers presented different methods for estimating technical losses (TLs) in distribution networks. Due to load variation during normal operation, load factor (LF) and loss factor (LSF) coefficients are considered. In this paper, the effect of repairing fault periods (RFPs) on calculating the TLs for medium voltage feeders of ring distribution network is presented. For emphasizing this effect, comparisons between TLs calculation considering only normal operation period (NOP) and considering both NOP and RFP are introduced. A proposed factor is suggested to be inserted into equations of TLs calculation to express the effect of RFPs. A proposed formula is introduced to calculate the new factor depending on repairing fault hours over the year. An actual ring distribution network in Egypt is chosen for evaluating the proposed study according to real data and measurements.

Model-free estimation of available power using deep learning

Abstract. In order to assess the level of power reserves during down-regulation, the available power of a wind turbine needs to be estimated. The current practice in available power estimation is heavily dependent on the pre-defined performance parameters of the turbine and the curtailment strategy followed. This paper proposes a single-input model-free approach dynamic estimation of the available power using recurrent neural networks. Accordingly, it combines wind turbine control considerations and modern forecasting methodologies for a model-free, single-input estimation of available power. It enables a robust real-time implementation of dynamic delta control, as well as higher-accuracy provision of the reserves to the system operators. The model-free approach requires only 1 Hz wind speed measurements as input and estimates 1 Hz available power as output. The neural network is trained, tested and validated using the DTU 10 MW reference wind turbine HAWC2 model under realistic atmospheric conditions. The unsteady patterns in the turbulent flow are represented via long short-term memory (LSTM) neurons which are trained during a period of normal operation. The adaptability of the network to changing inflow conditions is ensured via transfer learning, where the last LSTM layer is updated using new measurements. It is seen that the sensitivity of the networks to changing wind speed is much higher than that of turbulence, and the updates are to be implemented solely based on the altering inflow velocity. The validation of the trained LSTM networks on time series with 7, 9 and 11 m s−1 mean wind speeds demonstrates high accuracy (less than 1 % bias) and capability of transfer-learning online. Including highly turbulent inflow cases, the networks have shown to comply with the most recent grid codes, which require the quality of the available power estimations to be evaluated with high accuracy (less than 3.3 % standard deviation of the error around zero bias) at 1 min intervals.

Study on the Girder-End Displacement of a Suspension Bridge Based on Field Measurements

The load-response correlation is a great concern for the management and maintenance agency of bridges. Based on both the load test data and the long-term structural health monitoring data, this study aims to characterize the variation in the girder-end longitudinal displacement of a long-span suspension bridge, i.e., the Zhaoyun Bridge in Guangdong Province of China. The load test provides a valuable chance to investigate the structural deformation in high loading levels, while the structural health monitoring system records the real-time, in-site, and long-term measurements in the normal operational stage of bridges. During the load test, the movement direction of the main girder is found to depend on the relative position of the center of gravity of the girder and the loading vehicles. However, over the period of normal operation, the quasi-static displacement at the ends of the main girder along the bridge axis is dominated by the temperature variations, rather than the traffic loading. The temperature-induced deformation is considerable so it should be filtered out from the structural total responses to highlight the live load effects or the anomalies of the bridge. As a case study, the temperature-displacement baseline model of the Zhaoyun Bridge is established and then utilized to identify the erroneous measurements in the structural health monitoring system. This paper serves as a reference for the structural behavior interpretation and performance evaluation of similar bridges.

Determination of cracking causes in building structural elements

The article deals with the problems of buildings built many years ago, in which current and major repairs were not carried out in an appropriate manner. At the same time, buildings experience various deformations, such as yield, heel, subsidence, deflections, bends, twists, distortions, horizontal displacements. The survey of residential buildings built in the 80s is described and the analysis of the results of the survey of one of these buildings is carried out. The theoretical problem of the distribution of moisture in depth and various degrees of soil moisture has been solved. The reasons for the appearance of cracks in structures and cracks between individual building elements are also determined. The survey of a 9-storey brick residential building, built in the late 80s, which is in the period of normal operation, is considered. At the same time, the considered building is operated with significant deviations from regulatory requirements. The causes of cracks in individual structures and cracks between individual elements in the building are found. The problem of the distribution of moisture in depth with local soaking is solved on the basis of a numerical method, and the character of soil moistening at different depths with different degrees of moistening and characteristics of the base soil is obtained.

Grey prediction analysis of cutoff wall affected by construction effect

The long-term stability analysis of cutoff wall affected by construction effect is crucial. The longterm stability of the cutoff wall of Daning Reservoir is mainly affected by the combined action of highway vehicle load, extreme highway load and water load under different water storage loads. In this paper, the prediction model and method of grey theory are used to predict the horizontal displacement at the top of the cutoff wall, the settlement at the top, the maximum principal stress of the reinforced concrete wall, and the maximum principal stress of the plastic concrete wall based on grey analysis with each storage and drainage cycle as the time series point combined with the actual situation of the project. The long-term stability of the cutoff wall under load is predicted and evaluated. The results show that the maximum stress of the monitoring 2 – 2 section cutoff wall gradually tend to be stable during the whole storage and drainage cycle. The limit maximum compressive stress of reinforced concrete wall is 4.320 MPa, and the limit maximum compressive stress of plastic concrete wall is 1.758 MPa. Judging from the material strength, the maximum principal stress is within the design strength of the material, and the plastic failure of the wall does not occur, indicating that the combined anti-seepage system of rigid cutoff wall and plastic cutoff wall adopted by the Daning Reservoir is stable and safe in the later normal operation period.

Impacts of the COVID-19 event on the NOx emissions of key polluting enterprises in China

The unprecedented cessation of human activities during the COVID-19 pandemic has affected China's industrial production and NOx emissions. Quantifying the changes in NOx emissions resulting from COVID-19 and associated governmental control measures is crucial to understanding its impacts on the environment. Here, we divided the research timeframe into three periods: the normal operation period (P1), the Spring Festival period (P2), and the epidemic period following the Spring Festival (P3). We then calculated the NOx operating vent numbers and emission concentrations of key polluting enterprises in 29 provinces and 20 industrial sectors and compared the data for the same periods in 2020 and 2019 to obtain the impacts of COVID-19 on industrial NOx emissions. We found that spatially, from P1 to P2 in 2020, the operating NOx vent numbers in North China changed the most, with a relative change rate of –33.84%. Comparing the operating vent numbers in P1 and P3, East China experienced the largest decrease, approximately –32.72%. Among all industrial sectors, the mining industry, manufacturing industry, power, heat, gas, and water production and supply industry, and the wholesale and retail industry, were the most heavily influenced. In general, the operating vent numbers of key polluting enterprises in China decreased by 24.68%, and the standardized NOx (w)5-day decreased by an average of −9.54 ± −6.00 due to the COVID-19 pandemic. The results suggest that COVID-19 significantly reduced the NOx emission levels of the key polluting enterprises in China.

Launch of the FarmConners Wind Farm Control benchmark for code comparison

Careful validation of the modelling and control actions is of vital importance to build confidence in the value of coordinated wind farm control (WFC). The efficiency of flow models applied to WFC should be evaluated to provide reliable assessment of the performance of WFC. In order to achieve that, FarmConners launches a common benchmark for code comparison to demonstrate the potential benefits of WFC, such as increased power production and mitigation of loads. The benchmark builds on available data sets from previous and ongoing campaigns: synthetic data from high-fidelity simulations, measurements from wind tunnel experiments, and field data from a real wind farm. The participating WFC models are first to be calibrated or trained using normal operation periods. For the blind test, both the axial induction and wake steering control approaches are included in the dataset and to be evaluated through the designed test cases. Three main test cases are specified, addressing the impact of WFC on single full wake, single partial wake, and multiple wake. The WFC model outcomes will be compared during the blind test phase, through power gain and wake loss reduction as well as alleviation of wake-added turbulence intensity and structural loads. The probabilistic validation will be based on the median and quartiles of the observations and WFC model predictions. Every benchmark participant will be involved in the final publication, where the comparison of different tools will be performed using the defined test cases. Instructions on how to participate are also provided on farmconners.readthedocs.io.

Исследование причин отказов цилиндропоршневой группы среднеоборотных двигателей

The article is focused upon the problems of reciprocating diesel engines. The main reason for the failure of cylinder-piston group (CPG) parts is insufficient strength, wear resistance, and resistance of the metal structure to vibration. There are studied the following periods of engine operation: running-in period; period of normal operation; period of intensive wear. In the burn-in period, the main cause of CPG failures is scuffing, when finger breaking or ring groove chipping take place. Sudden failures during normal operation occur due to the wear of the bushings to the limit size. In the third period of intensive wear the main cause of metal failures is the ultimate wear by cavitation erosion and breakage of the bushing collar. The block diagram of the CPG system with serial connection of elements is given. The rate of CPG failures is illustrated depending on the time of operation. It has been found that the failure rate during the running-in period due to scuffing is reduced because of stabilization of the structure, dimensions and mechanical properties of the piston at operating temperatures (300–350°C). The failure rate of the normal period of operation depends on the increase in the abrasive wear resistance of the metal of bushings, increased hardness, due to the replacement of gray cast iron with lamellar graphite by gray cast iron with vermicular graphite or by high-strength cast iron with spherical graphite inclusions. There are listed the positive and negative qualities of aluminum alloys in comparison with cast iron. Variants of damage to cylinder liners are considered in detail. The most dangerous defect in the bushing is the cracks in the upper liner collar, as a result of which about 40% of the cylinder bushings must be replaced. The formulas for calculating the actual wear rate of the CPG parts during the first (end of warranty periods), medium and major overhauls are given. The failure rate of the last period of operation (intensive wear) is reduced by reducing vibration in the CPG system, reducing the amplitude of forced vibrations and reducing the size of the thermal gap between the sleeve and the piston, increasing the rigidity of the sleeve. The rate of cavitation wear of modernized and conventional bushings is determined, the influence of the bushing stiffness on cracks under the shoulder and on cavitation wear up to the maximum permissible thickness is considered.

Multi-year diagnosis of unpredictable fouling occurrences in a full-scale membrane bioreactor

The membrane bioreactor (MBR) at the Traverse City Regional Wastewater Treatment Plant has experienced sudden and unpredictable periods of substantial permeability decline since 2011. Early observations detected irregularly-shaped Gram-positive bacteria that correlated with plant upsets. Use of biomolecular techniques, such as DNA sequencing of laboratory isolates and the mixed liquor microbial community, and fluorescent in situ hybridization, identified the dispersed organisms as members of the genus Staphylococcus. However, Staphylococcus species were consistently present during normal operation and therefore were more likely to be an indicator of the upset, not the cause. The results suggest that these microorganisms are responding to specific influent wastewater constituents. We chemically analysed seven mixed liquor samples from periods of permeability decline in 2017 and 2018, and four samples from a period of normal operation. During upset conditions, the total carbohydrate content exceeded that of normal operation by 40%. Additionally, mixed liquor calcium concentrations were 65% above normal during the upset in 2017. It is hypothesized and supported through multivariate statistical analysis and estimation of specific resistance to filtration values that a calcium-intermediated polymer bridging mechanism with extracellular polymeric substance constituents is a major contributor to fouling and permeability disruptions in the Traverse City MBR.