Ride-matching and routing optimisation: Models and a large neighbourhood search heuristic

This paper considers a ridesharing problem on how to match riders to drivers and how to choose the best routes for vehicles. Unlike the others in the literature, we are concerned with the maximization of the average loading ratio of the entire system. Moreover, we develop a flow-dependent version of the model to characterize the impact of pick-up and drop-off congestion. In another extended model we take into account the riders’ individual evaluation on different transportation modes. Due to the large size of the resulting models, we develop a large neighbourhood search algorithm and demonstrate its efficiency

Carbon-efficient deployment of electric rubber-tyred gantry cranes in container terminals with workload uncertainty

Rubber-tyred gantry cranes are one of the major sources of carbon dioxide emissions in container terminals. In a move to green transportation, the traditional diesel powered cranes are being converted to electric ones. In this paper, we study the deployment of electric powered gantry cranes (ERTGs) in container terminal yards. Cranes always move in-between blocks to serve different workload. ERTGs use electricity for most movements but switch to diesel engines to allow inter-block transfers between unaligned blocks. We exploit this feature and propose to consider simultaneously the CO2 emissions and workload delays to develop carbon-efficient deployment strategies. Moreover, unlike previous works we consider the workload uncertainty, and model the problem as a two-stage stochastic program. A sample average approximation framework with Benders decomposition is employed to solve the problem. Multiple acceleration techniques are proposed, including a tailored regularised decomposition approach and valid inequalities. A case study with sample data from a major port in East China show that our proposal could reduce significantly CO2 emissions with only a marginal compromise in workload delays. Our numerical experiments also highlight the significance of the stochastic model and the efficiency of the Benders algorithms

A vehicle routing problem with distribution uncertainty in deadlines

This article considers a stochastic vehicle routing problem with probability constraints. The probability that customers are served before their (uncertain) deadlines must be higher than a pre-specified target. It is unrealistic to expect that the perfect knowledge on the probability distributions of deadlines is always available. To this end, we propose a distributionally robust optimisation framework to study worst bounds of the problem, which exploits the moment information of the historical observations. This framework includes two steps. We first use Conditional Value-at-Risk (CVaR) as a risk approximation to the probability of missing customer deadlines. The resulting nonlinear model is then transformed into a semi-infinite mixed integer program, using the dual form of the CVaR approximation. A sample approximation approach is then used to address the computational challenges. As the standard CVaR approximation to probability constraints is rather conservative, we suggest a relaxation to the approximation and develop an iterative algorithm to find the right value of the parameter that is introduced to the relaxed CVaR constraints. The extensive numerical experiments show that the routing policies developed by the proposed solution framework are robust and able to achieve the required target, regardless of deadline distributions

Inhibition of fEPSPs by AMP or ATP is reduced by TNAP-I selectively in CD73^−/− slices.

<p>(a) Hippocampal slices from CD73^+/+ and CD73^−/− mice were superfused with 10 µM AMP as indicated by the horizontal bar. After 15 min recovery, slices were superfused with 10 µM AMP plus 10 µM TNAP-I as indicated by the second horizontal bar. <i>n</i> = 3 CD73^+/+ and 3 CD73^−/−. Significant differences between genotypes are indicated by dashed lines; <i>p</i><0.05; unpaired <i>t</i>-tests. (b) Hippocampal slices from CD73^+/+ and CD73^−/− mice were superfused with 10 µM TNAP-I and, after 10 min, with 10 µM ATP as indicated by the horizontal bars. <i>n</i> = 3 CD73^+/+ and 3 CD73^−/−. Significant differences between genotypes are indicated by dashed lines; <i>p</i><0.05; unpaired <i>t</i>-tests. (c) Inhibition of metabolism of [¹⁴C]AMP to [¹⁴C]adenosine, [¹⁴C]inosine and [¹⁴C]hypoxanthine by TNAP-I was determined using membrane preparations from cerebral cortices. <i>n</i> = 4 CD73^+/+ and 4 CD73^−/−. *<i>p</i><0.05, relative to absence of TNAP-I; unpaired <i>t</i>-test. Ado, adenosine; Ino, inosine; HX, hypoxanthine.</p

Inhibition by ATP of fEPSP recordings in hippocampal slices from CD73^+/+ and CD73^−/− mice.

<p>(a) Representative traces of fEPSPs; numbers 1–6 correspond to before and during superfusion of slices with ATP (10, 25, 50 or 100 µM) or ATP (100 µM) and DPCPX (1 µM) as indicated in (b). (b) The effect of ATP on fEPSP slope in hippocampal slices from CD73^+/+ and CD73^−/− mice. Horizontal lines represent the duration of superfusion with the indicated ATP concentrations. (c) Maximum inhibition of fEPSPs obtained with each concentration of ATP. <i>n</i> = 4 CD73^+/+ and 5 CD73^−/−.</p

Inhibition by ATP of fEPSP recordings in hippocampal slices from hENT1 Tg and Wt mice.

<p>(a) Representative traces of fEPSPs; numbers 1–6 correspond to before and during superfusion of slices with ATP (10, 25, 50 or 100 µM) or ATP (100 µM) and DPCPX (1 µM) as indicated in (b). (b) The effect of ATP on fEPSP slope in hippocampal slices from hENT1 Tg and Wt littermate mice. Horizontal lines represent the duration of superfusion with the indicated ATP concentrations. (c) Maximum inhibition of fEPSPs obtained with each concentration of ATP. <i>n</i> = 4 hENT1 Tg and 4 Wt.</p

Inhibition by adenosine of fEPSP recordings in hippocampal slices from CD73^+/+ and CD73^−/− mice.

<p>(a) Representative traces of fEPSPs; numbers 1–6 correspond to before and during superfusion of slices with adenosine (10, 25, 50 or 100 µM) or adenosine (100 µM) and DPCPX (1 µM) as indicated in (b). (b) The effect of adenosine on fEPSP slope in hippocampal slices from CD73^+/+ and CD73^−/− mice. Horizontal lines represent the duration of superfusion with the indicated adenosine concentrations. (c) Maximum inhibition of fEPSPs obtained with each concentration of adenosine. <i>n</i> = 3 CD73^+/+ and 3 CD73^−/−.</p

DPCPX and NBTI, but not AOPCP, affect inhibition of fEPSPs by ATP.

<p>Hippocampal slices from CD73^+/+ and CD73^−/− mice were superfused with (a) 1 µM DPCPX, (b) 100 nM NBTI or (c) 50 µM AOPCP as indicated by the horizontal lines. After 10 min (a, c) or 20 (b) min, 100 µM ATP was applied as indicated by second horizontal line. <i>n</i> = 3–4 CD73^+/+ and 3–4 CD73^−/−. *<i>p</i><0.05; two tailed <i>t</i>-test.</p

TNAP-I reduces oxygen-glucose deprivation (OGD)-induced decreases in fEPSP recordings from CD73^−/− mice.

<p>Slices were superfused with TNAP-I as indicated by the horizontal bar and were superfused with (a) hypoxic aCSF for 10 min or (b) hypoxic glucose-free aCSF for 3 min as indicated by the second horizontal bar. <i>n</i> = 6 CD73^+/+ or 7 CD73^−/− mice (a) or from <i>n</i> = 5 CD73^+/+ or 8 CD73^−/− mice (b). Significant differences between genotypes are indicated by dashed lines. <i>p</i><0.05; unpaired <i>t</i>-tests.</p

Effect of hypoxia or oxygen-glucose deprivation (OGD) on fEPSP recordings.

<p>(a) Slices were superfused with hypoxic aCSF for 10 min as indicated by the horizontal bar. <i>n</i> = 7 CD73^+/+ or 9 CD73^−/− mice. (b) Slices were superfused with hypoxic glucose-free aCSF for 3 min as indicated by the horizontal bar. <i>n</i> = 5 CD73^+/+ or 4 CD73^−/− mice. There were no significant differences between genotypes.</p