Search results for "Time horizon"
showing 7 items of 47 documents
Simultaneous Vehicle and Crew Routing and Scheduling for Partial- and Full-Load Long-Distance Road Transport
2013
AbstractThis paper studies a simultaneous vehicle and crew routing and scheduling problem arising in long-distance road transport in Europe: Pickup-and-delivery requests have to be fulfilled over a multi-period planning horizon by a heterogeneous fleet of trucks and drivers. Typically, in the vehicle routing literature, a fixed assignment of a driver to a truck is assumed. In our approach, we abandon this assumption and allow truck/driver changes at geographically dispersed relay stations. This offers greater planning flexibility and allows a better utilization of trucks, but also creates intricate interdependencies between trucks and drivers and requires the synchronization of their routes…
The Multi-period Multi-trip Container Drayage Problem with Release and Due Dates
2021
Abstract The Container Drayage Problem (CDP) aims at routing a fleet of trucks, based at a common terminal, to serve customers while minimizing the total travel distance. Each trip starts from and ends at the terminal, and handles a subset of customers. Each customer requires either that a container is picked up or delivered. We introduce a more realistic variant, i.e., the Multi-trip Multi-period CDP with Release and Due Dates (MM-CDP-RDD), in which the planning horizon is composed of several periods (days). On each day, each truck may perform more than one trip respecting the Release and Due Dates (RDD) associated with customer services, corresponding to the first and the last day on whic…
Changes in the African monsoon region at medium-term time horizon using 12 AR4 coupled models under the A1b emissions scenario.
2011
This study documents simulated precipitation and circulation changes through the 20C3M and A1b scenarios. It portrays a robust pattern, associating rainfall deficits in subtropical regions with rainfall excesses over West Africa, except in Northern Senegal and Mauritania, with a significant enhancement of both the April–June rainy season in 10/12 models and of the July–September rainy season in 8/12 models. Eastward to 5°W a northward shift in the latitude of the moisture flux convergence at 850 hPa is evident in 10/11 models (+0.58° in mean) and a southward shift in 6/11 models in the western region (−0.24°) is observed. Copyright © 2011 Royal Meteorological Society
The 'power' of tourism in Portugal
2012
The author analyses the upper tail of the distribution of tourism supply in Portugal from 2002 to 2009, using data from the Instituto Nacional de Estatística database. Tourism supply is defined in terms of the lodging capacity of hotel establishments in about 250 tourist destinations. The paper shows that the empirical distribution of tourism supply in Portugal is heavy-tailed and consistent with a power law behaviour in its upper tail. Such behaviour seems to be stable over the years, provided that, for the time horizon covered by the data sets, the scaling parameter is always close to the value of two. The power law hypothesis is tested positively through the use of graphical and analyti…
Financial crisis impact on sustainability reporting
2013
Purpose – The purpose of this paper is to shed some light on the effect of the current financial crisis on corporate social responsibility (CSR) reporting and CSR assurance strategies that companies disclose online to stakeholders, by dividing the time horizon into two periods, before 2008 and from 2008. Design/methodology/approach – The sample includes Spanish listed companies, differentiating CSR reporters from non CSR-reporters. Also distinguished in the CSR-reporters sample, are those companies that assure the CSR report from those that do not. The authors contrast whether there is a trend as regards CSR reporting and CSR assurance, depending on whether the crisis has already begun or …
Early Treatment in HCV: Is it a Cost-Effective Option from the Italian Perspective?
2016
Background: The aim of this study is to perform an economic analysis to estimate the cost-utility of the early innovative therapy in Italy for managing HCV-infected patients.Methods: The incremental cost-utility analysis was carried out to quantify the benefits of the early treatment approach in HCV subjects. A Markov simulation model including direct and indirect costs and health outcomes was developed from Italian National Healthcare Service and societal perspective. 5,000 Monte Carlo simulations were performed on two distinct scenarios: Standard of Care (SoC) which includes 14.000 Genotype 1 patients in Italy treated with innovative interferon-free in the Fibrosis stage 3 and 4 (F3-F4) v…
Simultaneous optimization of harvest schedule and measurement strategy
2013
In many recent studies, the value of forest inventory information in the harvest scheduling has been examined. Usually only the profitability of measuring simultaneously all the stands in the area is examined. Yet, it may be more profitable to concentrate the measurement efforts to some subset of them. In this paper, the authors demonstrate that stochastic optimization can be used for defining the optimal measurement strategy simultaneously with the harvest decisions. The results show that without end-inventory constraints, it was most profitable to measure the stands that were just below the medium age. Measuring the oldest stands was not profitable at all. It turned out to be profitable t…