1,720,970 research outputs found
The multi-path Traveling Salesman Problem with stochastic travel costs
Full text linkGiven a set of nodes, where each pair of nodes is connected by several paths and each path shows a stochastic travel cost with unknown distribution, the multipath Traveling Salesman Problem with stochastic travel costs aims at finding an
expected minimum Hamiltonian tour connecting all nodes. Under a mild assumption on the unknown probability distribution a deterministic approximation of the
stochastic problem is given. The comparison of such approximation with a Montecarlo simulation shows both the accuracy and the eciency of the deterministic approximation, with a mean percentage gap around 2% and a reduction of the computational times of two orders of magnitude
Packing problems in Transportation and Supply Chain: new problems and trends
Full text linkEven if packing problems are, from their beginning, strictly linked to Transportation, the recent advances in this field (Smart City, Last Mile integration, City Logistics) and long-term planning of cross-country deliveries are forcing researchers towards a broader definition of them. In particular, while traditionally researchers mainly studied cutting and loading issues, with a special focus on the packing representation and the introduction of packing constraints like guillotine cuts, rotation and incompatibility between items, only recently they have started to consider more general issues as multi-attributes problems, rich packing problems, and uncertainty in the attributes. Aim of this work is to present the relevant literature, showing the different research directions as well as the new perspectives, with a special focus on tactical and strategic problem
Flights and their economic impact on the airport catchment area: an application to the Italian tourist market
Full text linkThe Cagliari Airport impact on Sardinia tourism: a Logit-based analysis
Full text linkIn the field of air transportation management, traditionally, airlines have been the main actors in the process for deciding which new flights open in a given airport, while airports acted only as the managers of the operations. The changes in the market due to the introduction of low cost companies, with consequent reduction of the airports’ fares, as well as the increment of the density of regional airports in several European countries are modifying the mutual roles of airlines and airports. The final decision on new flight to be opened, in fact, is nowadays the result of a negotiation between airlines and airports. The airports must prove the sustainability on the new routes and forecast the economic impact on their catchment area. This paper contributes to advance the current state-of-the-art along two axes. From the pure transportation literature point of view, we introduce a Logit model able to predict the passengers flow in an airport when the management introduces a change in the flight schedule. The model is also able to predict the impact of this change on the airports in the surrounding areas. The second contribution is a case study on the tourist market of the Sardinia region, where we show how to use the results of the model to deduce the economic impact of the decisions of the management of the Cagliari airport on its catchment area in terms of tourists and economic growth
The multi-path Traveling Salesman Problem with stochastic travel costs Models, methods and City Logistics applications
No full textFlights and their economic impact on the airport catchment area: an application to the Italian tourist market
Full text linkTraditionally, in the field of air transportation management airlines have been the main actors in the process of deciding which new flights to open in a given airport, while airports acted only as the managers of the operations. The changes in the market due to the introduction of low cost companies, with the consequent reduction of airports fares, as well as the increase in density of regional and secondary airports in many European countries are modifying the mutual roles of airlines and airports. Today, the final decision on new flights to be opened is the result of a negotiation between airlines, airports, and public stakeholders. The airports must prove the sustainability of the new routes and forecast the economic impact on their catchment area. This paper contributes to advance the current state-of-the-art providing a standard methodology to analyze the economic impact of flights and new airport routes. Subsequently, the methodology is applied to the summer tourism market in Sardinia and the winter tourism market in the North of Italy, in order to verify the adaptability of our approach to different characteristics of the tourist market
E-grocery and last mile logistics: do we need a supply-chain reference model?
No full textE-grocery is a new emerging and challenging business channel for the food & beverage market, enabling the consumers to purchase grocery products online. It combines the criticalities of distribution in urban areas (last mile logistics) with the distribution of fresh and perishable foods. In fact, several e-grocery companies already exist all around the world, but a large number of them have failed because of the high cost and complexity in the fulfillment of online orders and distribution activities, which significantly affect e-grocery profitability. A similar type of business is the Local Food Supply Chain (LFSC). This business concerns the local production and delivery of food to the consumers. It can assist local food producers in delivering goods in a more economically and environmentally efficient way, as well as offering to consumers the possibility of online purchasing, high quality, healthy and green foods and products from local producers. In the literature, several papers analyze e-grocery supply chains, identifying different order fulfillment and delivery options. It emerges as a key issue the importance of designing a profitable e-commerce business that combines a tailored value proposition and operational models. Nevertheless, a framework of urban supply chain combined with a business model has not been proposed yet. Furthermore, while a great attention is paid for studying e-grocery distribution as an online version of supermarket, fresh food and LFSC are somehow less considered. This paper aims to discuss whether a new supply-chain reference model for e-grocery is useful. First, we examine the solutions proposed in the literature, showing their benefits and limits. Second, due to peculiarities of the market under study and the lack of other work similar to the present paper, we propose a reference model dedicated to the e-grocery of LFSC. Our model incorporates innovative distribution and business models based on ICT and mobile applications in order to overcome criticalities related to order placement and home deliverie
Ambulance protocols: A mobile solution
No full textAbstract
The paper illustrates a pilot study involving nurses and paramedic staff to evaluate a mobile platform for rendering and distributing emergengy care protocols. Its specific features were developed to simplify the consultation and reduce the factors that negatively affect the adherence to standards. The study was planned to last one month and two questionnaires are administered to the participants: one at the starting phase, pre-intervention, and one at the end, post-intervention. Here we report the results and considerations coming from the first administration
Simulation of new policies for the baggage check in the security gates of the airports: the Logiscan case study
Full text linkIn recent years, the trend to mix in the same airports legacy and low-cost companies is heavily affecting the airport operations, stressing the security checks in particular. In fact, low-cost companies force the airports to add additional and strict rules for the hand baggage allowance, with additional checks in the security gates, introducing delays for all the passengers, including the legacy ones. Moreover, recent changes to the rules for hand luggage allowance introduced by legacy airlines are forcing the airport operations management to think of new strategies to automate the entire security check process. One of the most advanced systems presently available to speed up the security operations is Logiscan, developed by Datalogic e Logital in collaboration with the "Aeroporto Guglielmo Marconi di Bologna S.p.A.", the company managing the Bologna Airport. The system automates the operations of size and weight measures and allowance checks and, in conjunction with a redesign of the queuing system, aims to improve the overall system efficiency in terms of accuracy and efficiency. In order to check the new overall system, the entire process has been modeled and analyzed by means of AirSIM, a simulation tool for airport operations based on the well-known OMNeT++ Discrete Event Simulator. AirSIM is an object-oriented simulator able to describe the behavior of different passenger types, as well as to incorporate the logic of different flow management policies. In this paper we will show both how AirSIM can be used to analyze and choose the different parameters of the new security system of an airport, and how the overall system performances can be enhance
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