Data-driven models for microscopic vehicle emissions

In this paper, a new approach for describing the relationship between tailpipe emissions and vehicle movement variables is presented, called generalized additive model for location, scale and shape (GAMLSS). The dataset for this model is second-by-second emission laboratory measurements, following a real driving cycle that were recorded in urban, suburban and motorway areas of London. The GAMLSS emission model estimates each of CO_{2}, CO and NO_{x} in each second for two different vehicle types (petrol or diesel) using instantaneous speed and acceleration as the explanatory variables. Comparing the results with current emission models indicates substantial improvement in accuracy and quality of estimation by this approach

A genetic locus and gene expression patterns associated with the priming effect on lettuce seed germination at elevated temperatures

Seeds of most cultivated varieties of lettuce (Lactuca sativa L.) fail to germinate at warm temperatures (i.e., above 25–30°C). Seed priming (controlled hydration followed by drying) alleviates this thermoinhibition by increasing the maximum germination temperature. We conducted a quantitative trait locus (QTL) analysis of seed germination responses to priming using a recombinant inbred line (RIL) population derived from a cross between L. sativa cv. Salinas and L. serriola accession UC96US23. Priming significantly increased the maximum germination temperature of the RIL population, and a single major QTL was responsible for 47% of the phenotypic variation due to priming. This QTL collocated with Htg6.1, a major QTL from UC96US23 associated with high temperature germination capacity. Seeds of three near-isogenic lines (NILs) carrying an Htg6.1 introgression from UC96US23 in a Salinas genetic background exhibited synergistic increases in maximum germination temperature in response to priming. LsNCED4, a gene encoding a key enzyme (9-cis-epoxycarotinoid dioxygenase) in the abscisic acid biosynthetic pathway, maps precisely with Htg6.1. Expression of LsNCED4 after imbibition for 24 h at high temperature was greater in non-primed seeds of Salinas, of a second cultivar (Titan) and of NILs containing Htg6.1 compared to primed seeds of the same genotypes. In contrast, expression of genes encoding regulated enzymes in the gibberellin and ethylene biosynthetic pathways (LsGA3ox1 and LsACS1, respectively) was enhanced by priming and suppressed by imbibition at elevated temperatures. Developmental and temperature regulation of hormonal biosynthetic pathways is associated with seed priming effects on germination temperature sensitivity

A decomposition approach for signal optimisation in road networks

The optimisation of signal timings plays an important role in the management of urban traffic, and in the full usage of existing and planned road networks. In recent years, considerable advances have been made in techniques for the optimisation of signal timings at isolated junctions operating under fixed-time control. This paper shows how these techniques can be applied in the optimisation of signal timings in coordinated networks by using a decomposition approach. The signal timings at a junction in a network can be specified fully by the sequence of stages, interstage structures, cycle time, stage durations and offset. Of these variables, the third, fourth and last are endogenous to network optimisation methods, the first and second being exogenous. Techniques have been developed recently to optimise all but the last variable (which is not there defined) at individual junctions, and these have been found to give considerable improvements in operational performance. The computational requirements of these methods is such that their direct extension to networks is not yet a practical proposition. This paper shows how the differences inherent between individual junction and network optimisation methods can be reconciled within a decomposition approach so that the latter can benefit from some of the advantages of the former. A simple example is used to illustrate the substantial benefits that can arise from this approach.

Analysis of dynamic traffic equilibrium with departure time choice

We present and analyse a model of the combined choice of departure time and route in a congested road network. Using the property of equilibrium solutions that for each origin-destination pair the total cost associated with travel is identical for all travellers, we establish a general result that relates assignments to various components of cost. The analysis is developed to include time-varying tolls and to establish a formula that will induce any specified inflow profile as an equilibrium. We introduce an iteration operator to calculate equilibrium inflow profiles, and present the results of example calculations for a range of test problems