Warranty Terms Research Articles

Import substitution of elevator equipment in public procurements: problems and directions of stimulation

The problem of import substitution is relevant for any country, taken into account the requirements of its economic self-sufficiency, independence on the situation at the international markets and on geopolitical changes. For Ukraine in the state of full-scale war, this task is important from the viewpoints of economic resilience and security. For this reason, the Government determined the substitution of import components in public procurements as one of the priorities of its activity. Solving this problem will be important for the projects associated with the procurement for the recovery of infrastructure in post-war period. The sector of elevator equipment production has a significant industrial potential for the post-war recovery of infrastructure in Ukraine. Extension of industrial capacity of this segment of machine building in order to cover the domestic market requirements in post-war recovery period will enable new job creation and will provide a multiplicative effect based on the development of complementary suppliers of production components. However, a number of problems prevents Ukrainian elevator equipment producers from winning in public procurements. The goal of the article is to substantiate the reasonability and to determine the directions and stimulating measures for elevator equipment import substitution in public procurements in Ukraine. The market of elevator equipment of Ukraine has been analyzed. The capacity of Ukrainian elevator equipment producers to compete at the domestic market has been assessed based on price, warranty terms, cost of warranty service, and quality of equipment. Public procurement of elevator equipment and maintenance services in “Prozorro” system has been studied. It was found that about 70 % of public procurements of elevator equipment account for the purchases of imported equipment from Turkey and China. The problems of domestic producers of elevator equipment preventing them from winning the public procurement have been explained. The multiplicative effect from the increase of public procurements of elevator equipment from national producers has been assessed. This proves the reasonability to stimulate import substitution of elevator equipment in public procurements. The directions and measures of elevator equipment import substitution stimulation in public procurements in Ukraine have been suggested.

A Study on Evaluating Criteria for Electric Bicycle Purchase using ISM and ANP Methods

This study explores the increasingly complex nature of product design in customer-oriented industries due to the diversification and complexity of customer demands. The multiplicity of customer expectations complicates product design decisions. The aim of this study is to deeply understand the attributes of customer demand when purchasing electric bicycles, and to integrate Interpretive Structural Modelling (ISM) and Analytic Network Process (ANP) to assess the impact and interrelationships of these attributes. ISM is used to calculate the relationships between attributes, while ANP ensures the consistency and accuracy of evaluation weights to identify the priority improvement sequence most valued by customers. The study identifies five major evaluation criteria for electric bicycles: functionality, price and brand perception, practicality and performance, aesthetics, and safety. Among these criteria, safety emerges as the most prominent concern for customers, focusing primarily on the reliability of braking systems, antiskid tires, and nighttime riding lights. Following safety, practicality and performance considerations include factors such as range, charging time, vehicle weight, maximum speed, and climbing capability. Functionality ranks third in customer preferences, highlighting the importance of diverse features such as electric assist modes, multi-speed transmissions, and suspension systems. In terms of price and brand perception, consumers not only consider price competitiveness and brand reputation but also place significant emphasis on the completeness of after-sales service and warranty terms. Lastly, while aesthetics holds a relatively lower weight in overall criteria, consumer interest in exterior design and color coordination directly impacts product marketability and consumer purchasing decisions. In conclusion, these research findings provide crucial market insights to manufacturers, guiding product design directions and adjustments in market strategies to enhance product competitiveness and overall customer satisfaction,

How Credible Is the 25-Year Photovoltaic (PV) Performance Warranty?—A Techno-Financial Evaluation and Implications for the Sustainable Development of the PV Industry

To support the bankability of PV projects, PV manufacturers have been offering some of the longest warranties in the world, typically in the range of 25–30 years. During the warranty period, PV manufacturers guarantee that the degradation of PV modules will not exceed 0.4–0.6% each year, or the buyer can at any time make a claim to the manufacturer for replacement or compensation for the shortfall. Due to PV popularity, the performance warranty terms have become more and more competitive each year. However, long-term PV operating data are very limited, and the bankruptcy of PV manufacturers has been quite common. Without a proper methodology to assess the adequacy of the warranty fund (WF) reserves of PV manufacturers, the 25-year performance warranty can reflect an empty promise. To ensure sustainable development of the PV industry, this study develops a probability-weighted expected value method to determine the necessary WF reserve based on benchmark field degradation data and a prevailing degradation cap of 0.55% per year. The simulation results show that, unless the manufacturer’s degradation pattern is significantly better than the benchmark degradation profile, 1.302% of the sales value is required for the WF reserve. To the best of our knowledge, this is the first study that provides WF reserve requirement estimation for 25-year PV performance warranties. The results will provide transparency for PV investors and motivation for PV manufacturers to engage in continuous quality improvement, as all such achievements can now be reflected in the annual report results of manufacturers.

Pattern analysis of auto parts failures in the after-sales service network; an interconnected approach of association rules mining and Bayesian networks in the automotive industry

PurposeWarranty-based big data analysis has attracted a great deal of attention because of its key capabilities and role in improving product quality while minimizing costs. Information and details about particular parts (components) repair and replacement during the warranty term, usually stored in the after-sales service database, can be used to solve problems in a variety of sectors. Due to the small number of studies related to the complete analysis of parts failure patterns in the automotive industry in the literature, this paper focuses on discovering and assessing the impact of lesser-studied factors on the failure of auto parts in the warranty period from the after-sales data of an automotive manufacturer.Design/methodology/approachThe interconnected method used in this study for analyzing failure patterns is formed by combining association rules (AR) mining and Bayesian networks (BNs).FindingsThis research utilized AR analysis to extract valuable information from warranty data, exploring the relationship between component failure, time and location. Additionally, BNs were employed to investigate other potential factors influencing component failure, which could not be identified using Association Rules alone. This approach provided a more comprehensive evaluation of the data and valuable insights for decision-making in relevant industries.Originality/valueThis study's findings are believed to be practical in achieving a better dissection and providing a comprehensive package that can be utilized to increase component quality and overcome cross-sectional solutions. The integration of these methods allowed for a wider exploration of potential factors influencing component failure, enhancing the validity and depth of the research findings.

Optimal Decision for Repairable Products Sale and Warranty under Two-Dimensional Deterioration with Consideration of Production Capacity and Customers’ Heterogeneity

An effective warranty policy is not only an obligation for the manufacturer or vendor, but it also enhances the willingness of customers to purchase from them in the future. To earn more customers and increase sales, manufacturers or vendors should be inclined to prolong the service life of their products as an effort to gain more customers. Nevertheless, manufacturers or vendors will not provide a boundless warranty in order to dominate the market, since the related warranty costs will eventually exceed the profits in the end. Therefore, it is a question of weighing the advantage of extending the warranty term in order to earn the trust of new customers against the investment. In addition, since deterioration depends on both time and usage, the deterioration estimation for durable products may be incorrect when considering only one factor. For such problems, a two-dimensional deterioration model is suitable, and the failure times are drawn from a non-homogeneous Poisson process (NHPP). Moreover, customers’ heterogeneity, manufacturers’ production capacity, and preventive maintenance services are also considered in this study. A mathematical model with the corresponding solution algorithm is proposed to assist manufacturers in making systematic decisions about pricing, production, and warranty. Finally, managerial implications are also provided for refining related decision-making.

Warranty Cost Analysis for Multi-State Products Protected by Lemon Laws

The implementation of lemon laws in America has played an important role in improving the quality of after-sales service. Nowadays, many countries, such as China, Canada, Europe, Australia, Singapore, and South Korea, have adopted lemon laws in various industries to protect the interest of consumers. From the perspective of manufacturers, accurate estimation of the cost of the warranty service is of great importance in guiding product pricing, quality control, and design of warranty policies. According to the terms of different lemon laws, two warranty models considering the repair time and numbers for failures are proposed in this paper. Products under these models are multi-state, and Markov processes are used to model the degradation processes of products. In the first model, a product will be replaced by a new one if the time for a repair or the number of failures exceeds their respective thresholds over the warranty period. Under the second model, both catastrophic and minor failures are considered. A product will be replaced if one of the following three conditions is met over the warranty period: the time of one repair action (regardless of failure type) is longer than a time threshold; the number of minor failures is larger than a preset threshold; a catastrophic failure occurs. The expected warranty cost rates under the two proposed warranty models are derived under the assumption of renewable warranty terms. Numerical examples are given to illustrate the results obtained.

A photovoltaic degradation evaluation method applied to bifacial modules

The need to replace fossil energy sources with renewable energy sources to combat global warming has prompted the growth and development of various technologies, including photovoltaics. At the same time the PV technology is evolving to enhance efficiency and durability of PV modules. Bifacial PV modules is gaining larger share of market due to the higher energy and power density at almost the same price of conventional PV modules.In recent years, as PV systems have been operating for a long time, understanding the aging phenomenon of PV modules has become increasingly important. Various types of defects are known that occur during the life of the modules, however, understanding the trend of degradation through a simple quantification of the decrease in performance over time can be a useful tool. The Performance Loss Ratio can give indications about the state of health of the system and can be used for a rough comparison on the performance reduction guaranteed by the module manufacturer and check if the warranty terms are actually respected.In the present study a simple method is used to evaluate Performance Loss Ratio (PLR) on a real PV plant equipped with bifacial PERC modules.Criticalities were highlighted within each phase of the application of the method. The numerical results of the PLR estimate of the photovoltaic modules of the system are reported, calculated on a two-year dataset starting from the date of installation. Finally, the PLR values, that have been estimated using three different metrics and linear fitting, have been compared with the measured average Power decay values associated exclusively with PV modules.The simplicity of the method allows it to be replicated to other case studies.

Development of the State of Warranty (SOW) for Electric Vehicles

There is an exponential increase in electric vehicles on the road that need a follow up in terms of warranty. The proposed state of warranty (SOW) is a metastate that qualitatively describes the warranty fulfillment level of an electric vehicle. All the relevant warranty information is synthesized in a single merit while maintaining the level of detail through the qualitative substates. The developed SOW is calculated with a rule-based logic of an expert system that evaluates the quantitative value of three substates: the remaining warranty, the remaining health and the remaining useful warranty. The SOW provides a synthesized and user-friendly description of the warranty fulfillment state while providing quantitative detailed information of the most relevant features of each of the different maintenance methodologies.

Post-Warranty Replacement Models for the Product under a Hybrid Warranty

In this article, by considering both a limited number of failure replacements and a limited number of random working cycles as warranty terms, a hybrid warranty (HW) is designed from the manufacturer’s point of view to warrant the product that does successive projects at random working cycles. The warranty cost produced by HW is derived and analyzed. By defining that HW warrants the product, two types of post-warranty replacement models are investigated from the consumer’s point of view to ensure the reliability of the product through HW, i.e., customized post-warranty replacement and uniform post-warranty replacement. Depreciation expense is integrated into each post-warranty replacement. The expected cost rate model is presented for each post-warranty replacement and some special cases are obtained by setting parameters in the expected cost rate. Finally, sensitivities on both HW and post-warranty replacements are analyzed in numerical experiments. It is shown that when a limited number of failure replacements or/and a limited number of random working cycles are introduced to a warranty, the warranty cost can be reduced; and the performance of the uniform post-warranty replacement is superior to the customized post-warranty replacement.

Random replacement policies to sustain the post-warranty reliability

PurposeThe study aims to design the limited number of random working cycle as a warranty term and propose two types of warranties, which can help manufacturers to ensure the product reliability during the warranty period. By extending the proposed warranty to the consumer's post-warranty maintenance model, besides the authors investigate two kinds of random maintenance policies to sustain the post-warranty reliability, i.e. random replacement first and random replacement last. By integrating depreciation expense depending on working time, the cost rate is constructed for each random maintenance policy and some special cases are provided by discussing parameters in cost rates. Finally, sensitivities on both the proposed warranty and random maintenance policies are analyzed in numerical experiments.Design/methodology/approachThe working cycle of products can be monitored by advanced sensors and measuring technologies. By monitoring the working cycle, manufacturers can design warranty policies to ensure product reliability performance and consumers can model the post-warranty maintenance to sustain the post-warranty reliability. In this article, the authors design a limited number of random working cycles as a warranty term and propose two types of warranties, which can help manufacturers to ensure the product reliability performance during the warranty period. By extending a proposed warranty to the consumer's post-warranty maintenance model, the authors investigate two kinds of random replacement policies to sustain the post-warranty reliability, i.e. random replacement first and random replacement last. By integrating a depreciation expense depending on working time, the cost rate is constructed for each random replacement and some special cases are provided by discussing parameters in the cost rate. Finally, sensitivities to both the proposed warranties and random replacements are analyzed in numerical experiments.FindingsIt is shown that the manufacturer can control the warranty cost by limiting number of random working cycle. For the consumer, when the number of random working cycle is designed as a greater warranty limit, the cost rate can be reduced while the post-warranty period can't be lengthened.Originality/valueThe contribution of this article can be highlighted in two key aspects: (1) the authors investigate early warranties to ensure reliability performance of the product which executes successively projects at random working cycles; (2) by integrating random working cycles into the post-warranty period, the authors is the first to investigate random maintenance policy to sustain the post-warranty reliability from the consumer's perspective, which seldom appears in the existing literature.

Optimal condition-based warranty policy for multi-state products with three guarantees service

ABSTRACT Within a certain period of time after products are sold, many manufacturers offer free repairing, replacing and refunding for the defective products, referred to as three guarantees service. Under the assumption that the working states of the product can be partitioned into three non-overlapping sets and its degradation can be modeled by homogeneous Markov chain, a three-stage and conditioned-based warranty model is proposed. Under the model, the whole warranty period is divided into a compulsory replacement period, a condition-based maintenance period, and a minimal repair period. Over the condition-based maintenance period, depending on the state set that the working state before the failure belongs to, failed products are rectified minimally, imperfectly, replaced by an identical one and the warranty terms are renewed, respectively. Markov process and renewal process theories are used to analyze the failure process and the warranty servicing cost over the whole warranty period. Based on double Riemann sum, a recursive algorithm for finding the optimal partition method of working states and the warranty period is proposed. A numerical example is given to illustrate the validity of the warranty strategy.

Optimal warranty policy for repairable products with a three-dimensional renewable combination warranty

Nowadays, the post-sale warranty has become a crucial marketing strategy, and how to design and determine the optimal warranty policy has become one of the important issues for manufacturers. In the existing literature, warranty design and optimization mainly focus on one-dimensional and two-dimensional policies. However, as competition intensifies and customer requirements increase, product warranty terms usually involve three or more factors. In this paper, we propose a three-dimensional warranty policy for repairable products, in which limitations on failure time, repair time, and repair number are integrated. Considering the conflict between manufacturers and consumers, a novel renewable combination replacement warranty is further designed. By developing the corresponding sale price and warranty cost models, a profit optimization model is proposed. From the manufacturer’s perspective, the optimal warranty policy is obtained by maximizing the expected profit. A numerical example with sensitivity analysis and comparison studies is conducted to illustrate the proposed model. The results show that the proposed warranty policy can make the manufacturer more profitable and help to reduce the conflict between the manufacturer and the consumer.

Analysis of artificial intelligence in industrial drives and development of fault deterrent novel machine learning prediction algorithm

Industrial sectors rely on electrical inverter drives to power their various load segments. Because the majority of their load is nonlinear, their drive system behaviour is unpredictable. Manufacturers continue to invest much in research and development to ensure that the device can resist any disturbances caused by the power system or load-side changes. The literature in this field of study depicts numerous effects caused by harmonics, a sudden inrush of currents, power interruption in all phases, leakage current effects and torque control of the system, among others. These and numerous other effects have been discovered as a result of research, and the inverter drive has been enhanced to a more advanced device than its earlier version. Despite these measures, inverter drives continue to operate poorly and frequently fail throughout the warranty term. This failure analysis is used as the basis for this research work, which presents a method for forecasting faulty sections using power system parameters. The said parameters were obtained by field-test dataset analysis in industrial premises. The prediction parameter is established by the examination of field research test data. The same data are used to train the machine learning system for future pre-emptive action. When exposed to live data feeds, the algorithm may forecast the future and suggest the same. Thus, when comparing the current status of the device to the planned study effort, the latter provides an advantage in terms of safeguarding the device and avoiding a brief period of total shutdown. As a result, the machine learning model was trained using the tested dataset and employed for prediction purposes; as a result, it provides a more accurate prediction, which benefits end consumers rather than improving the power system's grid-side difficulties.

Optimization of Preventive Maintenance and Replacement Strategies for Nonrenewing Two-Dimensional Warranty Products Experiencing Degradation and External Shocks

“Vehicle damage insurance” in China, “Protection Plus Mobile Elite” launched by Samsung, “iPhone Apple Care +” offered by Apple, and so on are special warranty services aiming at external shocks. These warranty terms, named accident insurance, exist widely in the marketplace. Considering the effect of external shocks on degradation, a two-dimensional preventive maintenance and replacement strategy for products, sold with a nonrenewing and two-dimensional rectangle warranty service, is proposed in this paper. Under this strategy, preventive maintenance actions are scheduled based on units of age or usage, which occurs first. There is a reduction in the intensity function after a preventive maintenance action. Each shock before the Nth shock causes a failure of the product or an increase in product failure rate. The product is replaced by a new one on the Nth shock if it survives the N − 1 shocks. From the view of manufacturers, the mean warranty servicing cost over the whole warranty region is obtained by using the renewal theory. Based on direct numerical Riemann–Stieltjes integration, an approximation algorithm of the cost is also given. The mean cost is minimized by the optimization of preventive maintenance interval and the number of shocks N. A numerical example is given to illustrate the feasibility of the proposed strategy. The effects of maintenance cost, the arrival rate of the shocks, and other model parameters on the optimal strategy are also investigated numerically.

Random periodic replacement models after the expiry of 2D-warranty

The rapid development of advanced sensor technologies makes it possible to monitor the working cycle of products, which enables manufacturers to design warranty policies by monitoring working cycle during the warranty period and facilitates consumers to carry out post-warranty maintenance by tracking the post-warranty working cycle. The optimal warranty and maintenance policies considering random working cycles is rarely studied in existing literature. In this article, we make contribution by incorporating the limited number of random working cycle into a warranty term and proposing two types of two-dimensional warranty, which guarantees the product reliability performance by monitoring working cycle during the warranty period. Based on the proposed warranty policy, we further investigate the optimal post-warranty random maintenance policies from consumers’ perspective, including the random periodic replacement first and replacement last policies, which enhances the post-warranty reliability by monitoring the post-warranty working cycle. The warranty cost model is established under each proposed warranty policy, and the cost rate is evaluated under each post-warranty random maintenance policy. Some special cases of the established models are provided and discussed. By numerical experiments, we conduct sensitivity analysis of the proposed warranty and post-warranty random maintenance polices.

Procedure for the quantification of the degradation index of Photovoltaic Generators

A procedure is presented for the quantification of the degradation index of Photovoltaic Generators, based on the quantification of the operational losses inherent in the system, which allows maintaining the nominal operating conditions and by the warranty terms of the photovoltaic generator. A photovoltaic generator connected to the network with a nominal power of 7.5 kWp, installed in the Solar Energy Research Center of Santiago de Cuba, is used to evaluate and validate the procedure. The starting point is the mathematical model of the photovoltaic generator, then the operational losses of the photovoltaic generator are quantified and the mathematical model is adjusted to real conditions, through a polynomial adjustment. The results obtained show that the photovoltaic generator presents deviations in terms of the nominal power generation, because the operational losses are 7% with respect to the values ​​given by the manufacturer.

Identify the After-Sales Service Quality Factors, Influence the Repurchase Intentions of Selected White Goods

The expansion of the white goods industry is directly related to the level of consumer contentment, the quality of after-sale care, and the likelihood of future product purchases. To ensure customer happiness, businesses must do things like promptly replacing broken components throughout the product's warranty term and providing straightforward instructions for obtaining assistance. It is crucial for companies selling consumables like home items, pet food, cosmetic basics, and baby supplies to encourage consumers to renew their supply on a regular basis. This is the type of purchasing behavior that may increase ROI and guarantee long-term success. White-goods repurchase intent was analyzed in this research. Because of this, the Kendall's W test is used to determine whether or not there is a statistically significant difference between groups that otherwise seem the same.

Optimal price and warranty decision for durable products in a competitive duopoly market

In recent years, product warranties have become a promotional or competing instrument for the manufacturer. Although providing a warranty will benefit both transaction sides, it is impractical for the manufacturer to provide an unlimited warranty to monopolize the market since the related operating costs will eventually exceed the profits. Accordingly, to provide a proper warranty is a crucial issue for the manufacturer. However, the related studies overly focused on the issue of price competition. Actually, with regard to durable products, market competition exists in price and post-sale service. Accordingly, price and warranty should be equally important when manufacturers make their integrated marketing strategies. A rational non-cooperative game model will be proposed in this study. A duopoly market is considered, and the two manufacturers will pay the royalty to obtain critical techniques and parts from a technical supplier to produce and sell highly substitutable products to a local market. The study indicates as follows: once the duopoly market equilibrium is reached, no single manufacturer can increase its profits by means of raising its price or extending its warranty term since the two manufacturers’ decisions always react to each other. Moreover, the manufacturers cannot fully transfer the increment of the royalty to customers by means of raising price. In addition, increasing demand's competitive intensity with respect to warranty will amplify a manufacturer's warranty elasticity if its warranty term is shorter than that of its rival. Due to the practicality of this issue, more managerial insights and suggestions are included in this study.

Analysis of a two-dimensional stair-case warranty policy with preventive maintenance

Abstract We develop a mathematical model to study optimal preventive maintenance (PM) strategy under a two-dimensional stair-case warranty policy considering both age and usage of a product. During the warranty term, sellers implement preventive maintenance within the stair-case region of the warranty policy and upon failure a product is repaired minimally and immediately. Our objective is to find the optimal PM strategy that minimizes the seller’s cost of warranty while jointly considering the age and usage intervals of the PM policy and the level of PM executed. We also discuss how our results compare to those in a two-dimensional warranty policy with a rectangular region, and we find that the stair-case policy is preferable for sellers. An algorithm is provided to find the optimal solution and a numerical example is presented to illustrate how to find an optimal strategy with our proposed method. We show numerically that the expected total warranty cost is convex both in the age and the usage of the product under certain conditions.

Development of road transport infrastructure as a factor restoration of economic potential development of rural areas in Ukraine

The developed road transport infrastructure is a prerequisite for the economic and social development of the territories, in particular at the level of rural communities, as it allows creating conditions for comfortable living of the population, development of business initiatives, increasing the level of local accessibility of rural areas, and their investment attractiveness. The restoration of the economic potential of rural development in Ukraine objectively requires an in-depth study of the problematic aspects, obstacles and trends in the development of road transport infrastructure. The basis of the methodological basis for the study was the position of system-structural, comparative analysis and modern concepts of the institutional economy. The problematic aspects of the development of road transport infrastructure in the rural areas of Ukraine are identified, which are related to the neglect and low efficiency of the use of the end stops of the bus passenger transport, insufficient volumes of development and updating of roadside service facilities, low quality of passenger car transport, low quality of road works on the repair, construction and eradication of road friction, low efficiency of the public administration system motor roads, destruction of road construction due to increased weight loads on vehicles and traffic. The obstacles to improvement of road transport infrastructure in rural areas of Ukraine were identified: lack of practice of liquidation or legalization of spontaneous stops, lack of investments for their modernization; lack of effective interaction between local governments and executive authorities on the organization of passenger transportation and control over their functioning; lack of experience and non-compliance with standards for the development of road service facilities; deterioration of the network of highways; progressive aging of fixed assets and rolling stock of road enterprises; understatement of the warranty terms of the use of road surface. The directions of improvement of the state policy in the field of development of road transport infrastructure in the rural areas of Ukraine have been formed, which envisage the introduction of planning practices for the construction of objects of infrastructure of road objects, creation of incentives for carriers for the development of road transport infrastructure, approval of a regional program of development of highways of local the creation of transport and construction clusters at the subregional level, the introduction of new standards and qualifications conditions for conducting tenders for repairs, engineering and architectural arrangement of highways of local importance, the formation of databases of bona fide enterprises serving the road transport infrastructure, implementation of pilot projects in the field of reforming the existing system of road management in rural areas.