Search results for " data"
showing 10 items of 7516 documents
Financial Structure of the Family Business: Evidence From a Group of Small Spanish Firms
2007
This article presents empirical evidence on the determinants of the financial behavior of small family businesses and their differences from nonfamily small businesses. Taking into account two consolidated financial approaches, (1) the trade-off theory and (2) the pecking order theory, several hypotheses on the financial behavior of both groups of firms have been tested. By estimating these models through panel data methodology, using a sample of Spanish family businesses together with another control group of nonfamily businesses, we have obtained results confirming that a business's family nature does lead it to employ financial policy different from the rest of businesses. Furthermore, …
Micro and Macro Resilience Measures of an Economic Crisis
2020
Using Italian Households Budget Survey data over the period 1997-2013, a Cragg model in a life-cycle context is specified to compare the consumption behaviour in the pre- and post-crisis time and develop different micro and macro measures of resilience against crisis shocks. Cohort profiles for participation in and for consumption of tourism services in the pre- and post-crisis time are determined so as to explore the households’ resilience by generations. Next, the households’ resilience according to socio-demographic characteristics is addressed. As for the macro-resilience, combining individual expenditure elasticity, we examine whether and how Italian regions have responded to the recen…
Does higher technical efficiency induce a higher service level? A paradox association in the context of port operations
2020
Abstract Researchers and practitioners are benchmarking technical efficiency of ports and exploring the drivers of high efficiency. Paradoxically, this study argues that high technical efficiency (TE = 1) is not always essential, but an optimal level needs to be achieved while balancing the port service level. This study applies data envelopment analysis (DEA) and free disposal hull (FDH) methods to perform efficiency rankings of 38 container terminals from 17 different ports in 12 Asian countries. Four terminals are technically efficient (TE = 1) in all frontier approaches, thereof one Bangladeshi, one Chinese, one Indian and one Vietnamese. Furthermore, this study presents a case study co…
Novel Distance Estimation Methods Using 'Stochastic Learning on the Line' Strategies
2018
In this paper, we consider the problem of Distance Estimation (DE) when the inputs are the $x$ and $y$ coordinates (or equivalently, the latitudinal and longitudinal positions) of the points under consideration. The aim of the problem is to yield an accurate value for the real (road) distance between the points specified by the latter coordinates. 1 This problem has, typically, been tackled by utilizing parametric functions called the “Distance Estimation Functions” (DEFs). The parameters are learned from the training data (i.e., the true road distances) between a subset of the points under consideration. We propose to use Learning Automata (LA)-based strategies to solve the problem. In par…
Measuring foreland container port connectivity disaggregated by destination markets: An index for Short Sea Shipping services in Spanish ports
2020
Abstract The present research aims to develop a Foreland Port Connectivity Index (FPCI) including both qualitative and quantitative variables related to the characteristics of the maritime services provided. To that end, the FPCI incorporates two discount factors—the number of shipping services and destination countries—as penalties to correct for the quality of a port connection. After defining the FPCI, the index is applied to Spanish ports to study their connectivity in terms of container Short Sea Shipping (SSS) services. Although the connectivity of SSS traffic has not been widely studied, it is an interesting case study as small ports play a more relevant role in facilitating access t…
A more efficient cutting planes approach for the green vehicle routing problem with capacitated alternative fuel stations
2021
AbstractThe Green Vehicle Routing Problem with Capacitated Alternative Fuel Stations assumes that, at each station, the number of vehicles simultaneously refueling cannot exceed the number of available pumps. The state-of-the-art solution method, based on the generation of all feasible non-dominated paths, performs well only with up to 2 pumps. In fact, it needs cloning the paths between every pair of pumps. To overcome this issue, in this paper, we propose new path-based MILP models without cloning paths, for both the scenario with private stations (i.e., owned by the fleet manager) and that with public stations. Then, a more efficient cutting plane approach is designed for addressing both…
Branch-price-and-cut algorithms for the pickup and delivery problem with time windows and multiple stacks
2016
Abstract This paper proposes models and algorithms for the pickup and delivery vehicle routing problem with time windows and multiple stacks. Each stack is rear-loaded and is operated in a last-in-first-out (LIFO) fashion, meaning that when an item is picked up, it is positioned at the rear of a stack. An item can only be delivered if it is in that position. This problem arises in the transportation of heavy or dangerous material where unnecessary handling should be avoided, such as in the transportation of cars between car dealers and the transportation of livestock from farms to slaughterhouses. To solve this problem, we propose two different branch-price-and-cut algorithms. The first sol…
New exact methods for the time-invariant berth allocation and quay crane assignment problem
2019
Abstract Efficient management of operations in seaport container terminals has become a critical issue, due to the increase in maritime traffic and the strong competition between ports. In this paper we focus on two seaside operational problems: the Berth Allocation Problem and the Quay Crane Assignment Problem, which are considered in an integrated way. For the continuous BACAP problem with time-invariant crane assignment we propose a new mixed integer linear model in which the vessels can be moored at any position on the quay, not requiring any quay discretization. The model is enhanced by adding several families of valid inequalities. The resulting model is able to solve instances with u…
Irregular packing problems: a review of mathematical models
2020
Abstract Irregular packing problems (also known as nesting problems) belong to the more general class of cutting and packing problems and consist of allocating a set of irregular and regular pieces to larger rectangular or irregular containers, while minimizing the waste of material or space. These problems combine the combinatorial hardness of cutting and packing problems with the computational difficulty of enforcing the geometric non-overlap and containment constraints. Unsurprisingly, nesting problems have been addressed, both in the scientific literature and in real-world applications, by means of heuristic and metaheuristic techniques. However, more recently a variety of mathematical …
The Chinese Postman Problem with Load-Dependent Costs
2018
[EN] We introduce an interesting variant of the well-known Chinese postman problem (CPP). While in the CPP the cost of traversing an edge is a constant (equal to its length), in the variant we present here the cost of traversing an edge depends on its length and on the weight of the vehicle at the moment it is traversed. This problem is inspired by the perspective of minimizing pollution in transportation, since the amount of pollution emitted by a vehicle not only depends on the travel distance but also on its load, among other factors. We define the problem, study its computational complexity, provide two mathematical programming formulations, and propose two metaheuristics for its soluti…