We consider a supply chain in which a distributor procures from a producer a quantity of a fresh product, which has to undergo a long‐distance transportation to reach the target market. During the transportation process, the distributor has to make an appropriate effort to preserve the freshness of the product, and his success in this respect impacts on both the quality and quantity of the product delivered to the market. The distributor has to determine his order quantity, level of freshness‐keeping effort, and selling price, by taking into account the wholesale price of the producer, the cost of the freshness‐keeping effort, the likely spoilage of the product during transportation, and the possible demand for the product in the market. The producer, on the other hand, has to determine the wholesale price based on its effect on the order quantity of the distributor. We develop a model to study this problem, and characterize each party's optimal decisions in both decentralized and centralized systems. We further develop an incentive scheme to facilitate coordination between the two parties. Computational results are reported to show the effects of freshness‐keeping efforts.
Establishing a reliable chronological framework for sediments is crucial to the reconstruction of evolution process of estuarine delta, and the study of regional paleoenvironmental history, e.g., sea level fluctuations due to global climatic changes. High resolution chronology is still very limited for Holocene sediments in the Pearl River delta (PRD) in southern China. This study tries to construct a detailed chronology for core DA of 37.7 m in depth by using luminescence (seven samples) and radiocarbon (fourteen samples) dating techniques. Our results indicate that both luminescence and radiocarbon dating methods are suitable for the Holocene sediments in the PRD and that sediments of core DA were deposited during 7.3-0.18 ka. The 14 C age is generally older than the OSL age for the sediment at the similar depths, and the age difference increased from 0.45 ka at the depth of 21 m to 0.98 ka at the depth of 35 m. The reason that 14 C ages are relatively older might be caused by the carbon-reservoir effect which requires further study. The sedimentation rate increased from 3.74 m/ka during 7.3-2 ka to 7.92 m/ka in the last 2 ka. The appearances of rusty stains in upper unit of the core revealed that the water level was gradually falling. After the formation of underwater sand body at about 2 ka, the sediment was subject to continuous shifting between submergence and exposure.
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