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[en] Warranty claims are not always due to product failures. They can also be caused by two types of human factors. On the one hand, consumers might claim warranty due to misuse and/or failures caused by various human factors. Such claims might account for more than 10% of all reported claims. On the other hand, consumers might not be bothered to claim warranty for failed items that are still under warranty, or they may claim warranty after they have experienced several intermittent failures. These two types of human factors can affect warranty claim costs. However, research in this area has received rather little attention. In this paper, we propose three models to estimate the expected warranty cost when the two types of human factors are included. We consider two types of failures: intermittent and fatal failures, which might result in different claim patterns. Consumers might report claims after a fatal failure has occurred, and upon intermittent failures they might report claims after a number of failures have occurred. Numerical examples are given to validate the results derived.
[en] When a repairable item fails under warranty, the manufacturer has the option of either repairing the failed item or replacing it with a new one. In this paper, a repair-replace strategy is discussed for the manufacturer of a product sold with a two-dimensional warranty. The strategy is based on a specified region of the warranty defined in terms of age and usage with the first failure in the region rectified by replacement and all other failures being minimally repaired. An accelerated failure time (AFT) model is used to allow for the effect of usage rate on item degradation
[en] We discuss optimal software release problems which consider both a present value and a warranty period (in the operational phase) during which the developer has to pay the cost for fixing any faults detected. It is very important with respect to software development management that we solve an optimal software testing time by integrating the total expected testing cost and the reliability requirement. We apply a nonhomogeneous Poisson process model to the formulation of a software cost model and analyze three typical cases of the cost model. Moreover, we derive several optimal release polices. Finally, numerical examples are shown to illustrate the results of the optimal policies
[en] Chen and Popova [Res. Engng Syst. Saf. 77 (2002) 61] discuss maintenance policies for items sold with a two-dimensional warranty. However, their paper fails to give a proper review of the literature and it also contains errors. In this note we first review the relevant literature and then comment on the errors in their analysis
[en] Automobile warranty coverage is typically limited by age as well as mileage. However, the age is known for all sold vehicles at all times, but mileage is only observed for a vehicle with a claim and only at the time of the claim. We study the relationship between the expected number/cost of warranty claims and the driving patterns. Within a nonparametric framework, we account for the rate of mileage accumulation and propose a measure for the variability of this rate over a vehicle's observable life. We illustrate the ideas with real warranty data and comment on the relationship between the expected number/cost of warranty claims and the driving patterns using results adjusted/unadjusted for withdrawals from the warranty coverage due to mileage accumulation
[en] A number of optimal maintenance policies have been proposed and studied based on several types of warranty policies. As the criteria for optimality, the expected cost rate per unit time during the life cycle of the system is quite often used by many authors. However, the expected cost rate may depend on the length of life cycle and so the definition of life cycle plays a significant role in optimizing the maintenance policy. This paper considers a system maintenance policy during the post-warranty period under the renewing warranty policy and the life cycle is defined from the user's perspective. The life cycle starts with the installment of a new system and ends when the system is replaced by a new one at the expense of the user. In many renewing warranty models, the life cycle is defined as the lifelength of the new system installed initially, which is quite different from our definition. The expected cost rate per unit time is evaluated based on the life cycle newly defined and is compared with the existing results.
[en] Whether the goal is customer loyalty to a competitive energy service provider or customer satisfaction with monopoly distribution services, service guarantees must be seen as one way a company can communicate with its customers about the relationship it has (or wants) with them. In short, service guarantees must be evaluated as part of a company's overall brand management strategy. To do this, a conceptual framework within which to develop and link models of service delivery and brand management is needed. This means seeing both as examples of inference management. In this article the authors first interpret findings from their research on utility service guarantees in light of the model of service delivery proposed by Smith, Bolton, and Wagner. The authors then situate this model within their own model of utility brand management. The resulting approach can be used by a utility to evaluate whether and how to adopt service guarantees as part of its overall branding strategy
[en] Warranty data contain useful information about product quality and reliability, but they are usually coarse data because they may be aggregated, delayed, censored, missing or vague. They might, however, be the only forms of warranty data a manufacturer has, analysing such data are therefore needed and can also be of benefit to manufacturers in identifying early warnings of abnormalities in their products, providing useful information about failure modes to aid design modification, estimating product reliability for deciding on warranty policy, and forecasting future warranty claims needed for preparing warranty reserves plans. In last two decades, considerable research has been conducted in analysing coarse warranty data (CWD) from several different perspectives. This paper categorises different types of CWD and reviews techniques to analyse such data. It concludes with research needs in CWD. -- Highlights: ► To review existing research on warranty data collection. ► To classify warranty data into different categories. ► To find knowledge gaps. ► To propose future research
[en] With the phasing-out of the industrial use of nuclear energy for the power generation, the risk of the nuclear power plants has not been eliminated in principle, but only for a limited period of time. Therefore, the remaining nine nuclear power plants must also be used for the remaining ten years according to the state of science and technology. Regulatory authorities must substantiate the safety requirements for each nuclear power plant and enforce these requirements by means of various regulatory measures. The consequences of Fukushima must be included in the assessment of the safety level of nuclear power plants in Germany. In this respect, the regulatory authorities have the important tasks to investigate and assess the security risks as well as to develop instructions and orders.