On green routing and scheduling problem

The vehicle routing and scheduling problem has been studied with much interest within the last four decades. In this paper, some of the existing literature dealing with routing and scheduling problems with environmental issues is reviewed, and a description is provided of the problems that have been investigated and how they are treated using combinatorial optimization tools

When the path is never shortest: a reality check on shortest path biocomputation

Shortest path problems are a touchstone for evaluating the computing performance and functional range of novel computing substrates. Much has been published in recent years regarding the use of biocomputers to solve minimal path problems such as route optimisation and labyrinth navigation, but their outputs are typically difficult to reproduce and somewhat abstract in nature, suggesting that both experimental design and analysis in the field require standardising. This chapter details laboratory experimental data which probe the path finding process in two single-celled protistic model organisms, Physarum polycephalum and Paramecium caudatum, comprising a shortest path problem and labyrinth navigation, respectively. The results presented illustrate several of the key difficulties that are encountered in categorising biological behaviours in the language of computing, including biological variability, non-halting operations and adverse reactions to experimental stimuli. It is concluded that neither organism examined are able to efficiently or reproducibly solve shortest path problems in the specific experimental conditions that were tested. Data presented are contextualised with biological theory and design principles for maximising the usefulness of experimental biocomputer prototypes.Comment: To appear in: Adamatzky, A (Ed.) Shortest path solvers. From software to wetware. Springer, 201

An Agent-Based Approach to Self-Organized Production

The chapter describes the modeling of a material handling system with the production of individual units in a scheduled order. The units represent the agents in the model and are transported in the system which is abstracted as a directed graph. Since the hindrances of units on their path to the destination can lead to inefficiencies in the production, the blockages of units are to be reduced. Therefore, the units operate in the system by means of local interactions in the conveying elements and indirect interactions based on a measure of possible hindrances. If most of the units behave cooperatively ("socially"), the blockings in the system are reduced. A simulation based on the model shows the collective behavior of the units in the system. The transport processes in the simulation can be compared with the processes in a real plant, which gives conclusions about the consequencies for the production based on the superordinate planning.Comment: For related work see http://www.soms.ethz.c

Energy Utilization in Crop and Dairy Production in Organic and Conventional Livestock Production Systems

Searching for livestock production systems with a high energy utilization is of interest because of resource use and pollution aspects and because energy use is an indicator of the intensification of production processes. Due to interactions between crop and livestock enterprises and between levels of different input factors and their effects on yields, it is proposed to analyze agricultural energy utilization through system modelling of data from farm studies. Energy use in small grains, grass-clover and fodder beets registered in organic and conventional mixed dairy farms was analyzed and used together with crop yields in order to model energy prices on three Danish soil types. Conventional crop yields were higher but they also used more indirect energy with input factors, especially fertilizers. The conventional yields were not sufficiently higher to compensate for the extra use of energy compared with the organic crops. The organic crops had lower energy prices on all soil types, with the smallest difference on irrigated sandy soils. Sensitivity analyses were made for the effects of changes in irrigation and fertilizer levels. One conclusion was that better energy utilization in grain crops might be found at intermediate levels of fertilizer use, especially on irrigated soils. Actual farm diesel use was on average 47% higher than expected from standard values, suggesting that care should be taken when basing energetic analysis of farming methods on experimental data alone. On the same farms, the energy use in dairy production registered in organic and conventional mixed dairy farms was analyzed and used together with milk and meat yields in order to model energy prices for three different feeding strategies and two soil types. Conventional dairy production is more intensive with a greater feeding ration and a higher proportion of high-protein Seed, but has also higher yields. The conventional yields were not sufficiently higher to compensate for rite extra use of energy compared with the organic feeding ration. However, the loll er energy price in organic dairy production is dependent on the composition of the feeding strategy. Substitution of 500 SFU of grain with grass pellets makes an ordinary organic feeding ration based on conventional crop production competable. In general, the crop energy price models car? be used together with the dairy production to model the effects of different feeding and crop rotation strategies on the overall energy utilization in mixed dairy production systems