The purpose of this study is to investigate the impact that unevenly allocating buffer capacity has on throughput and average buffer level regarding unreliable lines to better understand the relevant factors in supply chain design. Results show that the best patterns for unreliable merging lines in terms of generating higher throughput rates (TR), as compared to a balanced merging line counterpart, are those where total available buffer capacity is allocated between workstations in either an inverted bowl pattern (i.e. concentrating buffer capacity towards the centre of the line), or a balanced line pattern. In contrast, when considering the trade-off between generating revenue resulting from TR and reducing cost created by average buffer levels (ABL), we found that the balanced pattern was not the best pattern. The best pattern was dependent on the length of the line and on the total buffer capacity as shorter lines with very constrained buffers were best served with an inverted bowl pattern while longer lines had the best results when applying an ascending buffer allocation pattern. Longer lines, in contrast, had the best results regarding the trade-off between TR and ABL, on average, by allocating buffer capacity evenly in one of the parallel lines while applying any other pattern in the remaining parallel line.
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Airport management is regularly challenged by the task of assigning flights to existing parking positions in the most efficient way while complying with existing policies, restrictions and capacity limitations. However, such process is frequently disrupted by various events, affecting punctuality of airline operations. This paper describes an innovative approach for obtaining an efficient stand assignment considering the stochastic nature of airport environment. Furthermore, the presented methodology combines benefits of Bayesian modelling and metaheuristics for generating solutions that are more robust to airport flight schedule perturbations. In addition, this paper illustrates that the application of the presented methodology combined with simulation provides a valuable tool for assessing the robustness of the developed stand assignment to flight delays.
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Aviation increasingly faces capacity challenges exposing inefficiencies and shortcomings of aviation related processes and systems. The European slot allocation system was designed in an era with little to no capacity constraints, now resulting in regulations not fitting in today’s developments.
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Modern airport management is challenged by the task of operating aircraft parking positions most efficiently while complying with environmental policies, restrictions, schedule disruptions, and capacity limitations. This study proposes a novel framework for the stand allocation problem that uses a divide-and-conquer approach in combination with Bayesian modelling, simulation, and optimisation to produce less-pollutant solutions under realistic conditions. The framework presents three innovative aspects. First, inputs from the stochastic analysis module are used in a multivariate optimisation for generating variability-robust solutions. Second, a combination of optimisation and simulation is used to finely explore the impact of realistic uncertainty uncaptured by the framework. Lastly, the framework considers the role of human beings as the final control of operational conditions. A case study is presented as a proof of concept and demonstrates results achievable and benefits of the framework proposed. The experimental results demonstrate that the framework generates less-pollutant solutions under realistic conditions.
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The aeronautical industry is still under expansion in spite of the problems it is facing due to the increase in oil prices, limited capacity, and novel regulations. The expansion trends translate into problems at different locations within an airport system and are more evident when the resources to cope with the demand are limited or are reaching to theirs limits. In the check-in areas they are appreciated as excessive waiting times which in turn are appreciated by the customers as bad service levels. The article presents a novel methodology that combines an evolutionary algorithm and simulation in order to give the best results taking into account not only the mandatory hard and soft rules determined by the internal policies of an airport terminal but also the quality indicators which are very difficult to include using an abstract representation. The evolutionary algorithm is developed to satisfy the different mandatory restrictions for the allocation problem such as minimum and maximum number of check-in desks per flight, load balance in the check-in islands, opening times of check-in desks and other restrictions imposed by the level of service agreement. Once the solutions are obtained, a second evaluation is performed using a simulation model of the terminal that takes into account the stochastic aspects of the problem such as arriving profiles of the passengers, opening times physical configurations of the facility among other with the objective to determine which allocation is the most efficient in real situations in order to maintain the quality indicators at the desired level.
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This study tackles the gate allocation problem (GAP) at the airport terminal, considering the current covid-19 pandemic restrictions. The GAP has been extensively studied by the research community in the last decades, as it represents a critical factor that determines an airport's capacity. Currently, the airport passenger terminal operations have been redesigned to be aligned and respect the covid-19 regulation worldwide. This provides operators with new challenges on how to handle the passengers inside the terminal. The purpose of this study is to come up with an efficient gate allocator that considers potential issues derived by the current pandemic, i.e., avoid overcrowded areas. A sim-opt approach has been developed where an evolutionary algorithm (EA) is used in combination with a dynamic passenger flow simulation model to find a feasible solution. The EA aims to find a (sub)optimal solution for the GAP, while the simulation model evaluates its efficiency and feasibility in a real-life scenario. To evaluate the potential of the Opt-Sim approach, it has been applied to a real airport case study.
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In November 2019, scholars and practitioners from ten higher education institutions celebrated the launch of the iKudu project. This project, co-funded by Erasmus [1], focuses on capacity development for curriculum transformation through internationalisation and development of Collaborative Online International Learning (COIL) virtual exchange. Detailed plans for 2020 were discussed including a series of site visits and face-to-face training. However, the realities of the COVID-19 pandemic disrupted the plans in ways that could not have been foreseen and new ways of thinking and doing came to the fore. Writing from an insider perspective as project partners, in this paper we draw from appreciative inquiry, using a metaphor of a mosaic as our identity, to first provide the background on the iKudu project before sharing the impact of the pandemic on the project’s adapted approach. We then discuss how alongside the focus of iKudu in the delivery of an internationalised and transformed curriculum using COIL, we have, by our very approach as project partners, adopted the principles of COIL exchange. A positive impact of the pandemic was that COIL offered a consciousness raising activity, which we suggest could be used more broadly in order to help academics think about international research practice partnerships, and, as in our situation, how internationalised and decolonised curriculum practices might be approached. 1. KA2 Erasmus+ Cooperation for innovation and the exchange of good practices (capacity building in the field of Higher Education)
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This research aims to find relevant evidence on whether there is a link between air capacity management (ACM) optimization and airline operations, also considering the airline business model perspective. The selected research strategy includes a case study based on Paris Charles de Gaulle Airport to measure the impact of ACM optimization variables on airline operations. For the analysis we use historical data which allows us to evaluate to what extent the new schedule obtained from the optimized scenario disrupts airline planned operations. The results of this study indicate that ACM optimization has a substantial impact on airline operations. Moreover, the airlines were categorized according to their business model, so that the results of this study revealed which category was the most affected. In detail, this study revealed that, on the one hand, Full-Service Cost Carriers (FSCCs) were the most impacted and the presented ACM optimization variables had a severe impact on slot allocation (approximately 50% of slots lost), fuel burn accounted as extra flight time in the airspace (approximately 12 min per aircraft) and disrupted operations (approximately between 31% and 39% of the preferred assigned runways were changed). On the other hand, the comparison shows that the implementation of an optimization model for managing the airport capacity, leads to a more balanced usage of runways and saves between 7% and 8% of taxi time (which decreases fuel emission).
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In 2005 and 2006, almost sixty Dutch National Sport Federations (NSFs) participated in a special program for creating a marketing strategy for the next four years. This program was initiated and organized by NOC*NSF (the Dutch Olympic Umbrella Sports Organization). The NSFs had to joint the project to receive funds. For most of them it was the first time they seriously analyzed the market with the aim of developing new programs. The purpose of this paper is to explore to what extent Dutch NSFs are capable to change their structures to become more market oriented and more market responsive in order to write strategic plans. The changed structures are investigated using the "institutional theory" (Tolbert & Zucker, 1996) and are explained by exogenous (market context and institutional context) and endogenous (interests, values, power dependencies, and capacity for action) dynamics from the neo-institutionalist framework (Greenwood & Hinings, 1996). In 2005 NSFs were expected to be in a pre-institutionalized stage, i.e. they were supposed to develop new organizational structures in response to specific problems (Kikulis, 2000). Now, approximately 1½ years after finishing their strategies, the question arises whether they have reached the semi-institutional stage, i.e. whether the new structures or actions are diffused across organizations, yet still subject to change and whether old structures are yet eroding (Kikulis, 2000). Methods Studying the intended structural change of NSFs requires an in-depth study of their social reality and the reactions and interpretations of involved actors, including their applied meanings to certain situations. Greenwood & Hinings (1996) plead for detailed comparative case-studies when studying institutional changes. Therefore three NSFs has been selected: The Royal Dutch Korfball Federation (KorfFed); The Royal Dutch Billiards Federation (BillFed); and the Dutch Jeu de Boules Federation (JeuFed). These three federations differ on size, amount of housed sports, number of associated clubs, sorts of intermediary decision making bodies, employed FTE's, and more. Therefore it is expected that the tempo of institutionalization of the new, market oriented, structures, will differ among them. Sugden & Tomlinson (2002) developed a multi-method style of qualitative research for making sense of the deep, inside information below the surface of everyday life. They call it the "Brighton method. Applying the Brighton method for this research implies that the three cases will be studied with respect to their history, their present marketing actions, their results and the changes in their organization. In-depth interviews, document analysis (policy plans, marketing plans and more), and where possible observations and participations are used to create a critical and investigative view of the organizations in change. Results The KorfFed used the marketing program to further develop existing programs. Although the outcomes of these programs were not new, the program has opened the eyes of the president, director and staff members. They are now conscious of the urgency of a market orientation, and a marketing orientation (a marketing position has already been introduced), and they see opportunities in attracting non-competition playing korfball players. They have, however, not yet reached the phase of semi-institutionalization of the market oriented structures. This can be concluded from the following: - The organization still has an ad-hoc character; - Some board members still make decisions based on their own insights rather than on information from the professional part of the organization; - Decisions to start programs are still grounded on subsidy possibilities rather than on market possibilities. Interest dissatisfaction and power dependencies are the main dynamics that form barriers in the planned organizational change. The BillFed is a federation that covers four disciplines, i.e. pool, snooker, carom, and billiard 3 cushions. The federation used to act upon these four disciplines. The marketing program has made clear that the BillFed should act upon target groups instead of on these disciplines. Therefore, the federation created a vision to reach youth, young adults, as also elderly people. Carrying out this new vision requires a market orientated structure (focus on target groups) instead of an internal orientated structure (focus on discipline groups). This new vision is created on an upper level (general board together with professional staff) in the organization. This federation also introduced a professional marketing position. Unfortunately, the underlying layers remain slightly passive and are not willing to work along the new structures, which mean that the new structures have not been diffused across the whole organization. Interest dissatisfaction, value commitments and power dependencies are the problematic dynamics. The JeuFed used to have a strong competition and tournament (internal) orientation, while many jeu-de-boules players play the game just for fun. The marketing program has created the insight that the just-for-fun players are also an important target group. Hence, 3 projects are developed to make club membership more attractive for all jeu-de-boules players. Since the federation never worked with projects before, they just found out that implementing projects such as these requires new structures. The JeuFed has just arrived in the pre-institutionalized phase, still far away from the semi-institutionalized chapter. Power dependencies and a lack of capacity for change are influencing dynamics in this case. Discussion Although it is already 1½ years ago that Dutch NSFs finished their marketing program, in none of the described cases the new structures have reached the semi-institutional stage. These new structures or actions are not yet diffused across the organizations, and the old structures are not eroding. In all three cases another combination of endogenous dynamics are influencing the process of organizational change. Continuing research is needed to find out whether these federations will ever reach the next stage of institutionalization and which dynamics will play an important role.
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Background: Research into termination of long-term psychosocial treatment of mental disorders is scarce. Yearly 25% of people in Dutch mental health services receive long-term treatment. They account for many people, contacts, and costs. Although relevant in different health care systems, (dis)continuation is particularly problematic under universal health care coverage when secondary services lack a fixed (financially determined) endpoint. Substantial, unaccounted, differences in treatment duration exist between services. Understanding of underlying decisional processes may result in improved decision making, efficient allocation of scarce resources, and more personalized treatment.
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