Browsing by Subject "Recycling"

Filter results by typing the first few letters
Now showing 1 - 4 of 4
  • Thumbnail Image
    ItemEmbargo
    Diffusion control in closed-loop supply chains: Successive product generations
    (Elsevier BV, 2023-12-10) Bayrak, B.; Guray, B.; Uzunlar, N.; Nadar, Emre
    We consider a durable-good producer who optimizes its sales decisions for two successive product generations with refurbishing and recycling potential. Customer arrivals follow a multi-generation diffusion process that takes into account the word-of-mouth feedback spread within each customer population of successive generations as well as the substitution effect among these generations. We investigate whether the producer can profit from partially satisfying the new-generation demand to slow down the product diffusion and improve the refurbishing and recycling volumes in the long run. We derive conditions for optimality of this partial-fulfillment policy. In fast-clockspeed industries, if the producer enters the refurbishing market for both generations, the partial-fulfillment policy is optimal if (i) the profit margin ratio of the early-generation product to the new-generation product is high enough, (ii) the profit margin ratio of the refurbished item to the new item is large enough for the new-generation product, and (iii) the fraction of customers willing to buy the refurbished item is only modestly large for each generation. If the producer uses the recycled content obtained from early-generation returns in new-generation production, the partial-fulfillment policy is optimal if (i) the number of early-generation end-of-life returns and the amount of recyclable material from each such return are large and (ii) the number of customers initially attracted by the early-generation product is high. We also characterize the critical time period beyond which initiating the partial-fulfillment policy provides no improvement in the refurbishing and recycling volumes for the new-generation product.
  • Thumbnail Image
    ItemOpen Access
    Diffusion control of successive product generations with recycling potential
    (2021-06) Uzunlar, Nilsu
    In this thesis, we study the sales planning problem of a producer who sells two successive generations of a durable good with recycling potential. Certain ex-pensive materials can be recovered from consumer returns of the early-generation product and can be used in manufacturing of the new-generation product. De-mands for the successive product generations arrive as a generalized Norton-Bass diffusion process and the recycling operations for the new-generation product are constrained by the early-generation product returns. In this setting, we inves-tigate whether slowing down the new-generation product diffusion by partially satisfying its demand might be profitable for the producer who aims to maximize its total profit from the entire product line. Such manipulation of the diffusion process may improve the use of recycled content in production as well as the cross-generation repeat purchases over a sufficiently long selling horizon. The optimal sales plan involves partial demand fulfillment when the diffusion curves of the early- and new-generation products overlap substantially and the release of the new-generation product only moderately increases the customer base. How-ever, partial demand fulfillment is less likely to be desirable if the product returns mostly arrive through trade-up programs rather than recycling programs such as free mail-back and physical drop-off options offered to consumers. Finally, partial demand fulfillment, if initiated too late, may escalate the overall consumption of virgin raw materials, making it environmentally undesirable.
  • Thumbnail Image
    ItemOpen Access
    Enhanced spontaneous emission in semiconductor nanocrystal solids using resonant energy transfer for integrated devices
    (IEEE, 2008-11) Nizamoğlu, Sedat; Demir, Hilmi Volkan
    Size-tuneable optical properties of semiconductor nanocrystal (NC) quantum dots make them attractive for a wide range of device applications. However, in these device applications, nanocrystals typically suffer from relatively low quantum efficiency (QE) when they are cast into solid form. To reduce the effect of this problem, we propose and demonstrate the enhancement of spontaneous emission in nanocrystal solids by recycling their trapped excitons through resonant nonradiative Forster energy transfer (ET) for hybrid integrated devices. For this purpose, we designed closely packed CdSe/ZnS core/shell nanocrystal emitters with an energy gradient of approximately 160 meV integrated on LEDs.
  • Thumbnail Image
    ItemOpen Access