Taking the distribution route optimization of refined oil as background, this paper studies the inventory routing problem of refined oil distribution based on working time equilibrium. In consideration of the constrai...Taking the distribution route optimization of refined oil as background, this paper studies the inventory routing problem of refined oil distribution based on working time equilibrium. In consideration of the constraints of vehicle capacity, time window for unloading oil, service time and demand of each gas station, we take the working time equilibrium of each vehicle as goal and establish an integer programming model for the vehicle routing problem of refined oil distribution, the objective function of the model is to minimize the maximum working time of vehicles. To solve this model, a Lingo program was written and a heuristic algorithm was designed. We further use the random generation method to produce an example with 10 gas stations. The local optimal solution and approximate optimal solution are obtained by using Lingo software and heuristic algorithm respectively. By comparing the approximate optimal solution obtained by heuristic algorithm with the local optimal solution obtained by Lingo software, the feasibility of the model and the effectiveness of the heuristic algorithm are verified. The results of this paper provide a theoretical basis for the scheduling department to formulate the oil distribution plan.展开更多
The Oak Ridge National Laboratory (ORNL) is the largest and most diverse energy, research, and development institution within the Department of Energy (DOE) system in the United States. As such, the site endures const...The Oak Ridge National Laboratory (ORNL) is the largest and most diverse energy, research, and development institution within the Department of Energy (DOE) system in the United States. As such, the site endures constant land development that creates rigorous growing conditions for urban vegetation. Natural resource managers at ORNL recognize that trees are an integral component of the landscape and are interested in characterizing the urban forest and their associated ecosystem services benefits. We evaluated the urban forest structure, quantified ecosystem services and benefits, and estimated economic value of resources using i-Tree Eco at ORNL. While this assessment captured over 1100 landscape trees, the ORNL Natural Resources Management for landscape vegetation can be expanded to include unmanaged landscapes, e.g. riparian areas, greenspace, and other vegetative attributes to increase ecosystem services benefits. Assigning a monetary value to urban forest benefits help to inform decisions about urban forest management, ideally on cost-benefit analysis.展开更多
Over the years, it appeared that firms failed to subject short-term investments to proper management thereby leading to either excessive or inadequate working capital which in turn affected their profitability. To emp...Over the years, it appeared that firms failed to subject short-term investments to proper management thereby leading to either excessive or inadequate working capital which in turn affected their profitability. To empirically satisfy this, this paper examined working capital management and firms’ profitability in Nigeria quoted firms on Nigerian Stock Exchange (NSE). A panel data methodology was used with different regression estimators to analyze this relationship based on a balanced panel of 10 listed firms during the period 2008-2017. It was discovered that cash collection period and cash payment period exerted a negative impact on return on assets, though the impact was only significant for cash payment period on the ground of −0.064 (p = 0.000 −0.032 (p = 0.077 > 0.05). Also discovered was that both the current ratio and inventory period exerted a positive impact on return on assets, though the impact was only significant for current ratio on the ground of 8.172 (p = 0.000 0.05). The study concluded that working capital management affected firms’ profitability in Nigeria. Therefore it was recommended that while the shorter collection was maintained, payment to creditors should not be elongated so as to enjoy cash discount (if any) and that firms should be proactive in the management of raw materials in order to avoid idle resources that might negatively impact their financial performance.展开更多
文摘Taking the distribution route optimization of refined oil as background, this paper studies the inventory routing problem of refined oil distribution based on working time equilibrium. In consideration of the constraints of vehicle capacity, time window for unloading oil, service time and demand of each gas station, we take the working time equilibrium of each vehicle as goal and establish an integer programming model for the vehicle routing problem of refined oil distribution, the objective function of the model is to minimize the maximum working time of vehicles. To solve this model, a Lingo program was written and a heuristic algorithm was designed. We further use the random generation method to produce an example with 10 gas stations. The local optimal solution and approximate optimal solution are obtained by using Lingo software and heuristic algorithm respectively. By comparing the approximate optimal solution obtained by heuristic algorithm with the local optimal solution obtained by Lingo software, the feasibility of the model and the effectiveness of the heuristic algorithm are verified. The results of this paper provide a theoretical basis for the scheduling department to formulate the oil distribution plan.
文摘The Oak Ridge National Laboratory (ORNL) is the largest and most diverse energy, research, and development institution within the Department of Energy (DOE) system in the United States. As such, the site endures constant land development that creates rigorous growing conditions for urban vegetation. Natural resource managers at ORNL recognize that trees are an integral component of the landscape and are interested in characterizing the urban forest and their associated ecosystem services benefits. We evaluated the urban forest structure, quantified ecosystem services and benefits, and estimated economic value of resources using i-Tree Eco at ORNL. While this assessment captured over 1100 landscape trees, the ORNL Natural Resources Management for landscape vegetation can be expanded to include unmanaged landscapes, e.g. riparian areas, greenspace, and other vegetative attributes to increase ecosystem services benefits. Assigning a monetary value to urban forest benefits help to inform decisions about urban forest management, ideally on cost-benefit analysis.
文摘Over the years, it appeared that firms failed to subject short-term investments to proper management thereby leading to either excessive or inadequate working capital which in turn affected their profitability. To empirically satisfy this, this paper examined working capital management and firms’ profitability in Nigeria quoted firms on Nigerian Stock Exchange (NSE). A panel data methodology was used with different regression estimators to analyze this relationship based on a balanced panel of 10 listed firms during the period 2008-2017. It was discovered that cash collection period and cash payment period exerted a negative impact on return on assets, though the impact was only significant for cash payment period on the ground of −0.064 (p = 0.000 −0.032 (p = 0.077 > 0.05). Also discovered was that both the current ratio and inventory period exerted a positive impact on return on assets, though the impact was only significant for current ratio on the ground of 8.172 (p = 0.000 0.05). The study concluded that working capital management affected firms’ profitability in Nigeria. Therefore it was recommended that while the shorter collection was maintained, payment to creditors should not be elongated so as to enjoy cash discount (if any) and that firms should be proactive in the management of raw materials in order to avoid idle resources that might negatively impact their financial performance.
