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Computers And Intractability A Guide To The Theory Of Np Completeness

Evolutionary food quality and location strategies for restaurants in competitive online-to-offline food ordering and delivery markets: An agent-based approach

This paper deals with automated guided vehicles (AGVs) which transport containers between the quai and the stack on automated container terminals. The focus is on the assigment of transportation jobs to AGVs within a terminal control system operating in real time. First, we describe a rather common problem formulation based on due dates for the jobs and solve this problem both with a greedy priority rule based heuristic and with an exact algorithm. Subsequently, we present an alternative formulation of the assignment problem which does not include due dates. This formulation is based on a rough analogy to inventory management and is solved using an exact algorithm. The idea behind this alternative formulation is to avoid estimates of driving times, completion times, due dates and tardiness because such estimates are often highly unreliable in practice and do not allow for accurate planning. By means of simulation, we then analyze the different approaches. We show that the inventory based model leads to better productivity on the terminal than the due date based formulation.

Inventory based dispatching of automated guided vehicles on container terminals

Container transportation has become an important part of global transportation and it may gain a new potential in the light of the Chinese One Belt One Road (OBOR) initiative, known in Europe also as the New Silk Road. It involves development of transport corridors – rail and maritime, linking China with Europe and it can be anticipated that its development will cause considerable shifts in container transportation from a sea into a rail (intermodal) route. In the light of substantial trade imbalance between Europe and China the problem of empty container repositioning gains specific importance. The aim of this study is the analysis of models and a variety of solutions to empty container repositioning problems through the prism of Eurasian intermodal transportation.

Approaches to empty container repositioning problems in the context of Eurasian intermodal transportation

This paper presents game-theoretical models based on a continuous approximation (CA) scheme to optimize service facility location design under spatial competition and facility disruption risks. The share of customer demand in a market depends on the functionality of service facilities and the presence of nearby competitors, as customers normally seek the nearest functioning facility for service. Our game-theoretical models incorporate these complicating factors into an integrated framework, and use continuous and differentiable density functions to represent discrete location decisions. We first analyze the existence of Nash equilibria in a symmetric two-company competition case. Then we build a leader–follower Stackelberg competition model to derive the optimal facility location design when one of the companies has the first mover advantage over its competitor. Both models are solved effectively, and closed-form analytical solutions can be obtained for special cases. Numerical experiments (with hypothetical and empirical data) are conducted to show the impacts of competition, facility disruption risks and transportation cost metrics on the optimal design. Properties of the models are analyzed to cast interesting managerial insights.

A continuum approximation approach to competitive facility location design under facility disruption risks

We present a survey of recent developments in the field of sequential competitive location problems, including the closely related class of voting location problems, i.e. problems of locating resources as the result of a collective election. Our focus is on models where possible locations are not a priori restricted to a finite set of points. Furthermore, we restrict our attention to problems defined on networks. Since a line, i.e. an interval of one-dimensional real space, may be interpreted as a special type of network and because models defined on lines might contain ideas worth adopting in more general network models, we include these models as well, yet without describing them in detail for the sake of brevity.

Sequential Competitive Location on Networks

We consider a flexible job shop scheduling problem with sequence-dependent setup times that incorporates heterogeneous machine operator qualifications by taking account of machine- and operator-dependent processing times. We analyze two objective functions, minimizing the makespan and minimizing the total tardiness, and present exact and heuristic decomposition-based solution approaches. These approaches divide the scheduling problem into a vehicle routing problem with precedence constraints and an operator assignment problem, and connect these problems via logic inequalities. We assess the quality of our solution methods in an extensive computational study that is based on randomly generated as well as real-world problem instances.

A worker constrained flexible job shop scheduling problem with sequence-dependent setup times

An exact solution approach for scheduling cooperative gantry cranes

Scheduling cooperative gantry cranes with seaside and landside jobs

In this paper we analyze the effect of including price competition into a classical (market entrant’s) competitive location problem. The multinomial logit approach is applied to model the decision process of utility maximizing customers. We provide complexity results and show that, given the locations of all facilities, a fixed-point iteration approach that has previously been introduced in the literature can be adapted to reliably and quickly determine local price equilibria. We present examples of problem instances that demonstrate the potential non-existence of price equilibria and the case of multiple local equilibria in prices. Furthermore, we show that different price sensitivity levels of customers may actually affect optimal locations of facilities, and we provide first insights into the performance of heuristic algorithms for the location problem.

Dominik Kress

Papers

Sequential Competitive Location on Networks

A worker constrained flexible job shop scheduling problem with sequence-dependent setup times

An exact solution approach for scheduling cooperative gantry cranes

Scheduling cooperative gantry cranes with seaside and landside jobs

Competitive Location and Pricing on Networks with Random Utilities