The existing outsourcing literature has generally overlooked the cost differential and contract negotiations between manufacturers and suppliers (by assuming identical cost structures and adopting the Stackelberg framework). One fundamental question yet to be addressed is whether upstream...

Here, we present a mathematical model for simulating both soil water flow and salt transport in two directions (perpendicular and parallel to the drip tubing) under mulched drip irrigation with saline water. We evaluated the effectiveness of this model by comparing the simulated values with...

Drought is one of the most harmful natural hazards in Gansu Province in Northwest China. The changes of precipitation affect the severity of drought. In order to recognize the trend of precipitation and understand the effect of rainfall change on water resources management and drought severity,...

We study an economy in which the rate of change of population depends on population policy decisions. This requires population as well as capital as state variables. By showing the algebraic relationship between the shadow price of the population and the shadow price of the per capita capital...

Conservation of the ecological environment presents scientists with a challenging dilemma because the strategy often leads to negative impacts on impoverished people in the area affected by the project. To consider this problem, we investigated the implications of China's national and regional...

This paper examines an integrated decision-making process regarding pricing for uncertain demand and sourcing from uncertain supply, which are often studied separately in the literature. Our analysis of the integrated system suggests that the base stock list price policy fails to achieve...

We deal with the problem of a profit-maximizing vendor selling a perishable product. At the beginning of a planning cycle, the vendor determines a minimum committed order per period. During the cycle, he may also place a supplemental order in each period based on the observed demand signal in...

In this paper, we consider a semi-on-line scheduling problem of two identical machines with common maintenance time interval and nonresumable availability. We prove a lower bound of 2.79129 on the competitive ratio and give an on-line algorithm with competitive ratio 2.79633 for this problem.

Transesterification of oil feedstocks using immobilized lipase (IL) is a promising process for biodiesel production. However, the running cost of this process is still higher than that of conversional chemical-catalyzed approaches. To address this challenge, both upstream and downstream...