A local search algorithm for finding optimal transit routes configuration with elastic demand

This paper proposes a new local search algorithm for finding the optimal configuration of subroutes from a set of candidate transit routes in a transportation network. It is intended to maximize the transit ridership while holding the budget constraint. In each iteration of the algorithm, route segments that are likely to absorb more transit passengers are added to the configuration and less‐contributing segments are removed, instead. A path‐based model with elastic demand is applied for traffic assignment problem. The algorithm takes advantage of the equilibrium paths information to speed up the calculations for emerging configurations. A numerical experiment on Sioux‐Falls network indicates that the proposed algorithm can achieve high‐quality solutions at different levels of budget. Also, the run‐time and performance of the algorithm are reported over a large problem instance of the Chicago sketch network with 55 artificial candidate routes.     

Alkyl ketene dimer modification of thermomechanical pulp promotes processability with polypropylene

Alkyl ketene dimers (AKDs) are known to efficiently react with cellulose with a dual polarity in their structure: a polar component and a nonpolar component. AKD of three different carbon chain lengths, 4, 10, and 16 carbons have been synthesized, and thermomechanical pulp (TMP) fibers were modified by them. The modification of TMP fibers with AKD resulted in an increased water contact angle, showing the presence of the AKDs on the TMP fibers and a new carbonyl peak in the IR spectra, suggesting modification of the TMP fibers with AKD groups. Calculating the Hansen solubility parameters of AKD and AKD conjugated to TMP in polypropylene (PP) indicates improved compatibility, especially of longer chain AKD and TMP AKD. The rheological studies of the composites showed that the AKD with the longest carbon chain decreases the melt viscosity of the PP-TMP-AKD composite, which combined with the shape and the color of the extruded composite filaments indicates improved flow properties and reduced stress build up during processing. The research findings demonstrate the ability of AKD to enhance the dispersibility and compatibility of natural fibers with PP.