Two Network Structure Indicators for Conventional Public Transit

The significance of network structure indicators for the planning and management of conventional public transit is widely acknowledged.In order to improve and enrich the conventional public transit assessment system,two network structure indicators are proposed.Firstly,according to the obvious defects lying in the traditional no-linear coefficient,the realistic no-linear coefficient γRNL,a modified no-linear coefficient indicator,is put forward,which takes into account the effects of barriers in a city.Secondly,to cover the gap of an indicator which can reflect the coverage homogeneity of a transit network,the length dimension LDis proposed on the basis of Fractal Theory.Finally,a case study is applied to verify the validity and practicability of the two indicators in problem diagnosis using regression analysis.The results validate that γRNLcan evaluate the detour of bus lines more reasonably than the previous no-linear coefficient because it reflects the layout of bus lines,and LDcan represent the rate of change of the network density,adding a new member to the scheme of network structure indicators for public transit.

Theoretical Study on the Kinetics for the Reactions of Heptyl Radicals with Methanol

Ab initio study of the reactions ofn-heptyl radicals（1-C7H15, 2-C7H15, 3-C7H15, and 4-C7H15） with metha- nol was conducted over the temperature range of 300--1500 K. Transition states for the reaction channels producing CTH15OH, CH3, C7H15OCH3, H, C7H16, CH2OH and CH30 were identified and the geometries of all stationary points were calculated at BB1K/MG3S level of theory. The potential barrier heights of the corresponding transition states were predicted by the CBS-QB3//BB1K and G4//BB1K methods, indicating that the eight H-abstraction channels are more kinetically favorable than the channels where OH transfers from CH3OH to C7H15 and where the CTHIsOCH3＋H products are given. Tile rate constants of H-abstraction channels were calculated with TST and TST/Eck. Both the forward and reverse rate constants have positive temperature dependence and the ttmneling effect is only important at the temperature lower than 700 K. For the reactions of H-atom abstraction from methyl in CH3OH by n-heptyl, a reverse and the corresponding forward rate constant are roughly equal. For the reactions of H-atom abstraction from OH in CH3OH by n-heptyl, a reverse rate constant is larger by several orders of magnitude thin1 the corresponding forward one.