For products sold with a two-dimensional warranty policy, the warranty servicing cost can be reduced through reliability growth during development. This paper investigates a multi-phase reliability growth test program for repairable products with independent competing failure modes.Considering a test-find-test scheme, an accelerated reliability growth model is developed, allowing different failure modes having distinct accelerated relationships. Taking usage heterogeneity and mode-specific failure learning effect into account, the reliability growth is achieved through periodic fixes on a phase-by-phase basis. From the manufacturer's perspective, the main objective is to achieve the optimal trade-off between the warranty cost and the reliability growth test cost by determining the optimal test program that minimizes the expected total cost per product sold, ensuring that the pre-specified reliability growth requirement is met. Assuming the tri-Weibull product failure distribution, we illustrate the proposed optimization model numerically and study the effect of relevant parameters on the optimal reliability growth test program. The results show that the proposed approach yields significant cost reduction and reliability improvement for the examples studied in this paper, especially when the manufacturer possesses high failure learning ability, and the product has expensive repair cost per a warranty failure and extensive warranty coverage.
Guided by the conviction that “Clear waters and green mountains are as good as mountains of gold and silver”, China highly values sustainable economic and social development through innovation and Internet technology. Regression analysis is performed to examine the impact of corporate information disclosure environment proxied by the Internet penetration rate on innovation. Leveraging from the city-level Internet penetration rates data in China from 2003 to 2017, this study gets the following findings: (1) Firms headquartered in cities with high Internet penetration rates tend to be more innovative, i.e. they invest more in research and development. (2) This result is supported by several robustness checks, such as alternative measures of key variables, alternative empirical specifications, and tests to mitigate identification concerns. (3) "financing constraint" and "tolerance of innovation failure" are two channels that influence firms’ innovative endeavors. (4) Additional tests show that Internet penetration rates facilitate a firm’s output efficiency of innovation input, total factor productivity, and human capital environment for innovation. The above conclusions not only enrich the relevant literature on the influencing factors of corporate innovation from the perspective of the firm information disclosure environment but also provide an important reference for further understanding the positive role of macro technology development on social and economic development.
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