Determination of optimal post-warranty variable maintenance period for repairable second-hand product based on mean residual life

Due to the increased transactions of second-hand products in the market, the optimization of maintenance strategy for the second-hand product has become very important issue to attract a great attention from many researchers of late. This paper proposes a new post-warranty strategy with a variable self-maintenance period for the second-hand product, assuming that the product is replaced by another one on the first failure following a fixed length of post-warranty self-maintenance period. During the non-renewing warranty period, the product is subject to preventive maintenance periodically at a prorated cost while only minimal repair is implemented at each failure by the dealer. The main goal of this study is to determine an optimal length of post-warranty self-maintenance period which minimizes the expected cost rate per unit time during the product’s life cycle from the user’s perspective. This approach considers not only the periodic preventive maintenance during the warranty period, but also the remaining life distribution of the product after the warranty expires, which is the significant difference of this work from many existing maintenance policies. For this purpose, we formulate the expected length of life cycle and evaluate the expected total cost incurred during the life cycle of the second-had product which is purchased at the age of [Formula: see text] The existence of the optimal self-maintenance period is proved analytically under mild conditions and the proposed maintenance model is compared with an existing model with regard to the expected cost rate. Finally, assuming that the life distribution of the product follows a Weibull distribution, the effect of relevant parameters on the optimal self-maintenance period is analyzed numerically.

Availability Optimization of Multicomponent Products with Economic Dependence under Two-Dimensional Warranty

For multicomponent products, the maintenance of every component separately will increase the downtime and reduce the availability of products during the warranty period. To solve this problem, the economic dependence between the components is considered in this paper. Firstly, a single-component two-dimensional (2D) preventive maintenance (PM) availability model is established, and the simulated annealing algorithm is adopted to calculate the optimal 2D PM interval to achieve the maximal availability of any single component. Then, to ensure that the warranty cost of each component does not exceed the budget, the PM benchmark interval is introduced, and the PM work is optimized following the method of grouping maintenance. Based on this, the 2D preventive grouping maintenance availability model of multicomponent products is established. Finally, an example is given to verify the proposed method, and the results indicate that the proposed method increases the availability of multicomponent products during the 2D warranty period.

The Right to Repair Goods in the Era of Digitalization and Globalization

Today, large companies are increasingly using controversial strategies related to the violation of the buyer’s rights to repair the goods both during and after the expiration of the warranty period. This is primarily manifested in the restriction of access to the necessary information on the product repairing, hindering the work of independent service organizations, intentional complication of parts during their design, unreasonably high degree of integration of units, lack of a sufficient number of spare parts on the market, etc. As a rule, such actions distort the principles of integrity and transparency, which, in turn, entails risks to consumer and environmental safety. This issue is of particular relevance in the context of the COVID-19 pandemic, when sellers of medical equipment restrict the possibility of its restoration by independent specialists, and also prevent the distribution of the necessary software. Based on the results of the work, it is concluded that it is advisable to establish boundaries for the conduct of market participants to stimulate the production of durable and maintainable goods in order to transit to a circular economy.

Analysis of the Impact of Input Data on the Planned Costs of Building Maintenance

The aim of the article is to analyze the method of determining the maintenance costs of buildings based on the method proposed in Polish legal regulations. The analysis of the sensitivity of the method shows that the assumed number of product use cycles during the calculation period has the greatest impact, while the adopted warranty period has the lowest impact. A multi-functional building combining housing, office, service and commercial was analyzed in order to obtain a broader picture of the model’s operation. The results of the analyses allow us to conclude that despite the higher price of materials, the most durable solutions, which are the most expensive to purchase, turn out to be the most advantageous in the entire life cycle of the building. The method proposed in Polish law regulations has certain limitations. In order to level them, it was proposed to extend the method by using NPV (Net Present Value) for calculations and extending the life cycle of the building to 80 years.

Use Of BIM In SLLC “Latvian State Roads” For Process Managment

BIM is an integrated set of building design, construction and management processes, technologies and regulations that allow all parties involved to jointly design, build and manage a building in a digital environment. In Europe, a common approach to the use and adaptation of technologies is currently being developed with the aim of providing a common regulatory framework that would promote the efficiency of technology application between the countries of the European Union. The use of BIM technologies is based on economic (financial) benefits. The financial benefits are estimated in the long run, and the main factors for financial savings are productivity and quality, which can be achieved by applying BIM technology and appropriate processes during the construction cycle (design, construction and management). Studies show that savings can reach up to 10% of construction costs. Currently underway is the process of implementing and configuring the Microsoft Dynamics platform for processing and using work information of SJSC "Latvian State Roads" (LSR). Microsoft Dynamics is a line of enterprise resource planning and customer relationship management software. In general, LSR intends to use the system in the following stages of the construction cycle: • Design stage • Construction procurement stage • Construction stage • Warranty period Microsoft Dynamic has both pros and cons for processing LSR information. Only after full implementation it will be possible to assess the effectiveness of this platform. Objective of the article is to explore how the use of BIM can improve the LSR work process and what happening at this moment in LSR.

Reliability of Electric Submersible Pumps ESP & Determination of Weibull Parameters for Failure Characterization, Ecuador Case Study

The current research focuses on data modeling of ESP (Electric Submersible Pumps) reliability by obtaining, through mathematical calculations, the parameters that define the Weibull shape (β), scale (ɳ) and location (ϒ) parameters. The scale parameter ɳ is the characteristic life at which 63.2% of the population has failed. These parameters can be helpful in characterizing failure behavior and the ESP system run life. This research stemed from the need to better understand failure behavior to improve maintenance program design and enhance equipment reliability.160 wells from four fields (7-21, 56, 57) of the Ecuadorian Oriente basin were analyzed. Well selection considered only the mechanic failures and excluded other type of failures leaving aside the ESP failures caused by operative issues (reservoir, completions, workover, redesign, zone change). Three mathematical tools were applied to determine the Weibull parameters more accurately. Another type of analysis could have limited this research since the normal distribution shows limitations with asymmetric data, and the exponential distribution assumes a fixed failure rate, but the ESP failure behavior is asymmetric and the failure rate is variable through time due to factors such as wear and also infant failures (e.g. installation errors). For these reasons, Weibull distribution is the best option because it fits asymmetric data better and it has a variable failure rate. Determining the value of the Weibull parameters can assist in answering questions such as: what percentage of failures is expected to occur in time? How many failures can be expected before the warranty period? When should regular maintenance be scheduled? Ultimately, Weibull parameters are the basis of any future reliability analysis. The Weibull parameters obtained in this study can be applied for future ESP reliability analyzes that are being operated in any field in the Oriente Basin of Ecuador. From the research, two relevant findings were foundThere are a significant number of failures in the initial stage of operation of the pumps,, which could be associated with the installation of the equipment, and the failure risk is drastically reduced in the equipment that reaches life time similar to the characteristic life (ɳ)and pumps that operate without failure to a time similar to characteristic life (ɳ) continue to follow this trend throughout their operating life. Initial stage failures are presumed to be associated with unanticipated conditions: solid binding, design errors, defective equipment, or assembly of equipment with reused and new parts. The performance of the ESP affects the productivity of the wells and therefore will influence decision-making to develop a field. The reliability of the ESP systems can favor the productivity of a field when the equipment works within its efficiency range without showing recurrent failures. This significantly improves field production costs and profitability.

FEATURES OF CONSTRUCTION AND TECHNOLOGY OF PANEL WOOD CONSTRUCTION ELEMENTS FOR JOINT-BUILDING PRODUCTS AND FURNITURE

Each industrial enterprise, in order to increase the competitiveness of its products, must ensure such quality indicators as dimensional stability and maintainability during the entire warranty period. In practice, these indicators are ensured by observing the design rules. This problem is especially relevant in the design of joinery and construction and furniture products operated in variable climatic conditions. The purpose of the study was to establish the optimal technological chains for the production of re-adhesive structural elements; find the optimal sizes of lamellas, plots and assembly units for gluing; substantiate the expediency of veneering the glued elements with sawn veneer; design of products as a whole without the use of spikes and glue. All studies were carried out in real production conditions: at LLC Firm "Caucasian Forest", Republic of Adygea, Maikop district, settlement Tulsky and LLC HC "Mebel Chernozemya ", Voronezh. It is clear from the studies carried out that the technology of re-glued blanks allows several times to reduce warpage and increase the dimensional stability of structural elements; veneering operation allows rational use of low-grade wood in production

Studying the Normal Operation of Grain Harvesters within the Warranty Period

Introduction. Grain harvesters are used for no more than two months within a year. They must have maximum operating reliability, since even short downtime during the harvesting period result in large crop losses. The purpose of the study is to identify the causes of combine harvester failures within the warranty period. Materials and Methods. Identifying consequences of failures and ensuring the reliability of grain harvesters are based on an improved classification of failures. In the process of studying, there have been proposed the ways to solve the problem of combine harvester downtime based on the analysis of the time for grain harvester troubleshooting. The category of severity of failure consequences was taken into account. Results. Through monitoring in the period from 2018 to 2020, there were found failures of units and systems of grain harvesters with low reliability indexes within the warranty period. Most of the failures (59.2%) were found in Russian-manufactured combines, of which operational failures are 55.9%, structural failures – 26.7%, and production failures – 17.4%. The general patterns of changes in the average time for combine troubleshooting have been determined. A geometric model of a detail for the trouble-free operation of combines (header auger shaft) was created. The finite element analysis (ANSYS) was used to identify parts, which are subject to maximum workload. There have been identified units and parts, which fail to function within the warranty period, because of design and technological defects. Discussion and Conclusion. In order to reduce the time to find the consequences of failures, it is necessary to create a more extensive network of enterprises providing a wide range of services, improve the organization of technical service and expand direct links with the manufacturers of equipment in order to respond quickly and make the necessary design and technological decisions.

A 7-year warranty period for chest pain patients with a non-ischaemic [15O]H2O positron emission tomography: a follow-up of 273 individuals

Funding Acknowledgements Type of funding sources: None. Background A normal perfusion scan is associated with a favourable outcome. The aim of the present study is to determine the warranty period of normal hyperemic myocardial blood flow (MBF) derived with quantitative [15O]H2O positron emission tomography (PET) in symptomatic individuals with cardiovascular risk factors. Methods A total of 539 patients referred for baseline adenosine [15O]H2O PET MBF imaging because of suspected coronary artery disease (CAD) were investigated. A PET scan was considered normal if the hyperemic MBF was > 2.3 ml/min/g. The warranty period was predefined as < 2% annual event rate. The primary endpoint was a composite of late revascularizations, myocardial infarction and all-cause mortality. Results In a total of 273 patients (mean age 57.2 ± 9.1; 34.4% male) with a normal PET scan, 19 events occurred during a median follow-up of 6.8 years (interquartile range 4.9-7.7). Events included 10 late revascularizations, 2 myocardial infarctions and 7 deaths. The annual event rate exceeded 2% in the 8th year of follow-up, resulting in a warranty period of 7 years (see Figure 1). Conclusion In patients referred for suspected CAD a normal hyperemic perfusion derived by [15O]H2O PET confers a 7-year warranty period against late revascularization, myocardial infarction and all-cause mortality.