Coordination in service supply networks:insights from “Airport Collaborative Decision Making”

We examine the relationship between governance (alignment of interests) and coordination (alignment of actions), of mutually-dependent organisations in extended service networks. Research on governance has explored the interplay of contractual and relational mechanisms, mainly in dyads. In service operations management, interaction between provider and customer is understood as ‘co-production of value’. We examine the link between the two, and how coordination is achieved among several closelyinterdependent organisations on a single site. ‘Collaborative Decision-Making’ practices in airport operations provides the setting for the study, and we propose an initial framework to explain the role of information sharing and coordination mechanisms

Change point for multinomial data using phi-divergence test statistics

We propose two families of maximally selected phi-divergence tests for studying change point locations when the unknown probability vectors of a sequence of multinomial random variables, with possibly different sizes, are piecewise constant. In addition, these test-statistics are valid to estimate the location of the change-point. Two variants of the first family are considered by following two versions of the Darling- Erdös' formula. Under the no changes null hypothesis, we derive their limit distributions, extreme value and Gaussian-type respectively. We pay special attention to the checking the accuracy of these limit distributions in case of finite sample sizes. In such a framework, a Monte Carlo analysis shows the possibility of improving the behaviour of the test-statistics based on the likelihood ratio and chi-square tests introduced in Horváth and Serbinowska (1995). The data of the classical Lindisfarne Scribes problem are used in order to apply the proposed test-statisticsMultinomial sampling, Change-point, Phi-divergence test-statistics

The multi-objective Steiner pollution-routing problem on congested urban road networks

This paper introduces the Steiner Pollution-Routing Problem (SPRP) as a realistic variant of the PRP that can take into account the real operating conditions of urban freight distribution. The SPRP is a multi-objective, time and load dependent, fleet size and mix PRP, with time windows, flexible departure times, and multi-trips on congested urban road networks, that aims at minimising three objective functions pertaining to (i) vehicle hiring cost, (ii) total amount of fuel consumed, and (iii) total makespan (duration) of the routes. The paper focuses on a key complication arising from emissions minimisation in a time and load dependent setting, corresponding to the identification of the full set of the eligible road-paths between consecutive truck visits a priori, and to tackle the issue proposes new combinatorial results leading to the development of an exact Path Elimination Procedure (PEP). A PEP-based Mixed Integer Programming model is further developed for the SPRP and embedded within an efficient mathematical programming technique to generate the full set of the non-dominated points on the Pareto frontier of the SPRP. The proposed model considers truck instantaneous Acceleration/Deceleration (A/D) rates in the fuel consumption estimation, and to address the possible lack of such data at the planning stage, a new model for the construction of reliable synthetic spatiotemporal driving cycles from available macroscopic traffic speed data is introduced. Several analyses are conducted to: (i) demonstrate the added value of the proposed approach, (ii) exhibit the trade-off between the business and environmental objectives on the Pareto front of the SPRP, (iii) show the benefits of using multiple trips, and (iv) verify the reliability of the proposed model for the generation of driving cycles. A real road network based on the Chicago's arterial streets is also used for further experimentation with the proposed PEP algorithm. © 2019 Elsevier Lt

Microfluidic converging-diverging channels optimised for performing extensional measurements

Microfluidics refers to the science and technology that deals with devices which manipulate and examine fluid flows in small scaled systems (1μm - 1000μm). The possibility of such microfabricated channels to replicate the natural environment at the dimensional scale of many biological and industrial processes, together with the small amount of volume sample they require, increased rapidly their popularity in many fields (i.e. biotechnology, engineering etc.). Additionally, microfluidics offers the ability to produce fluid flows that are characterised by high deformation rates under small Reynolds numbers (Re), offering a promising platform for investigating fluids described by complex rheological behaviour. That way, important viscoelastic effects

Optimisation of a microfluidic converging channel for extensional measurements

Strong extensional flows are important for many scientific and industrial applications, especially for non-Newtonian fluids where measurements of extensional properties, such as extensional viscosity, are important. Converging geometries are known for their ability to stretch the fluid in a strong extensional flow along the centreline [1]. At the macroscale, converging channels used as extensional rheometers are usually axisymmetric and operate only with highly viscous fluids to reduce inertial effects. Microfluidic flows are characterised by high deformation rates under small Reynolds numbers (Re),offering a promising platform for investigating fluids described by complex rheological behaviour

Developing a conceptual model for examining the supply chain relationships between behavioural antecedents of collaboration, integration and performance

Purpose – The purpose of this paper is threefold: first, review the literature on the topic of behavioural antecedents of collaboration and their impact on supply chain integration and performance; second, lay the theoretical foundations and develop a conceptual model linking behavioural antecedents of collaboration, information integration, coordination of operational decisions and supply chain performance; and third, set out operationalisation considerations. Design/methodology/approach – A conceptual model with theoretical basis on Relational Exchange Theory (RET) and extant supply chain theory is developed as a causal model that can be operationalised using structural equations modelling (partial least squares) and a “single key informant” approach. Findings – Positive relationships between behavioural antecedents of collaboration (trust, commitment, mutuality/reciprocity), information integration, coordination of operational decisions and supply chain performance (efficiency, effectiveness) are hypothesised. RET provides adequate theoretical background that leads to the theoretical establishment of hypotheses between behavioural antecedents, supply chain integration and performance, which are worth testing empirically. Research limitations/implications – The ideas presented in this paper enrich the study of behavioural factors in supply chain management and their impact on supply chain performance, and may benefit researchers in the field. The paper also sets the scene (experimental design, measurement items) for the upcoming field research. The empirical part of the work will provide the necessary evidence for the validation of the established hypotheses. Practical implications – The proposed linkages may stimulate the interest of supply chain strategists towards more collaborative relationship management and affect their decisions on the behavioural antecedents of relationship formation and management. Moreover, the proposed model may help clarify how the integration of critical operational contingencies – information, operational decisions – can help achieve superior supply chain performance. Originality/value – The paper establishes a causal relationship between constructs which have not been researched (mutuality/reciprocity, coordination of operational decisions) or have been researched individually or in combination (impact of integration on performance, impact of collaboration on performance) but not in the proposed integrated way. It also addresses the challenge of lack of theoretical justification on the development of knowledge that will assist decision making in SCM/logistics and its integration into models, processes and tasks. Finally, by using RET in selecting of behavioural factors and establishing hypotheses, it adds to the body of knowledge concerning the use of interorganisational theories in supply chain relationships

An integrated modelling approach for the bicriterion vehicle routing and scheduling problem with environmental considerations

The consideration of pollution in routing decisions gives rise to a new routing framework where measures of the environmental implications are traded off with business performance measures. To address this type of routing decisions, we formulate and solve a bi-objective time, load and path-dependent vehicle routing problem with time windows (BTL-VRPTW). The proposed formulation incorporates a travel time model representing realistically time varying traffic conditions. A key feature of the problem under consideration is the need to address simultaneously routing and path finding decisions. To cope with the computational burden arising from this property of the problem we propose a network reduction approach. Computational tests on the effect of the network reduction approach on determining non-dominated solutions are reported. A generic solution framework is proposed to address the BTL-VRPTW. The proposed framework combines any technique that creates capacity-feasible routes with a routing and scheduling method that aims to convert the identified routes to problem solutions. We show that transforming a set of routes to BTL-VRPTW solutions is equivalent to solving a bi-objective time dependent shortest path problem on a specially structured graph. We propose a backward label setting technique to solve the emerging problem that takes advantage of the special structure of the graph. The proposed generic solution framework is implemented by integrating the routing and scheduling method into an Ant Colony System algorithm. The accuracy of the proposed algorithm was assessed on the basis of its capability to determine minimum travel time and fuel consumption solutions. Although the computational results are encouraging, there is ample room for future research in algorithmic advances on addressing the proposed problem