Accurate forecasting in Reverse Supply Chain (RSC) management is crucial for the semiconductor industry, particularly for companies like ASML, which must efficiently manage the return flow of defective machinery parts. This study addresses key gaps by developing and evaluating time series-based forecasting models tailored to ASML's RSC. Using a modified ABC-analysis, parts were categorized based on defect frequency and economic impact, focusing on the most critical components. The research applied and optimized models including SES, ARIMA, ARIMAX, and LSTM, using five years of historical defect data. The analysis showed that LSTM models excel in high-frequency (weekly) forecasts for parts with frequent early-life defects, achieving an average mMAPE of 26.32\%. ARIMAX models performed best for lower-frequency (monthly) data, particularly in sparsely represented classifications, with mMAPE as low as 4.31\% to 10.80\%. Despite a higher mMAPE of 85.42\% in one outlier, ARIMAX emerged as the most balanced model, offering a practical trade-off between accuracy and computational efficiency. Furthermore, the study highlights the computational efficiency of ARIMAX, which, although more demanding than SES, provided a favorable balance, with ARIMA and LSTM being more resource-intensive. These findings demonstrate ARIMAX's suitability for long-term forecasting and broader trend analysis, making it the preferred model for ASML's RSC. This research provides a robust, data-driven framework that enhances inventory management and capacity planning, making it possible to predict return flows with low error rates on a monthly basis, particularly in high-tech industries where many defective parts are returned. Future research should incorporate additional dynamic variables, explore hybrid models, and refine data splitting techniques to further improve predictive accuracy and support sustainable supply chain operations.

Purpose: The construction industry is responsible for great amounts of resource consumption, waste generation and both carbon and greenhouse gas emissions in the European Union. The currently still predominant linear mindset of take-make-consume-dispose must shift to reduce the industry’s environmental impact and enable the transition towards a circular construction industry. Circular material hubs facilitate more circularity by collecting, processing, and redistributing secondary building components to make them available for another life cycle. In literature, little can be found about the system circular material hubs are embedded in and their connection to architects. This study investigates the system of circular material hubs in the Netherlands, its challenges, opportunities, and potential future developments in the transition towards a circular construction industry. A special focus is placed on the role of architects within this system, as a circular construction industry also needs designers to include secondary building components in designs. The Netherlands is one of the top nations in the reuse of secondary raw materials and therefore provides as an exemplary setting for this exploratory research.
Methodology: An exploratory, qualitative research approach was chosen. Fourteen semi-structured interviews were conducted with representatives from circular material hubs, architects, as well as experts in the fields of circular economy, circular construction industry and construction logistics. Practitioner interviews aimed at identifying practices performed within the system of circular material hubs, and detecting challenges, opportunities and potential future developments as perceived by practitioners in the field. Expert interviews were conducted to validate the information gathered through literature review and practitioner interviews.
Findings: The research found four practice bundles which are important for the system of circular material hubs. These practice bundles are acquisition practice, processing practices, sales practices, and material harvesting practices. Within these practice bundles, different practices and performances of these practices were identified. The practices influence each other. Which building components are acquired influences which processing practices need to be performed. The type of building component also influences the sales practice as different building components target different groups of clients and are sold through different communication channels. It is also crucial whether the building components are sold offline or online. The online marketplace of Insert was found to be particularly helpful, as it is specifically designed for the construction industry and used by circular material hubs as well as architects. This shows the influence of the choice of communication channel on a circular design practice and scouting practices. By providing as much information as possible about the secondary building component at hand, circular material hubs also facilitate a circular design practice. Additionally, challenges, opportunities, and potential future developments of the system of circular material hubs were identified. Challenges the system faces are related to uncertainty and irregular assortment, guidelines, costs, and the provision of guarantees, while opportunities are governmental decisions, the provision of information and the use of shared online marketplaces. Missing collaborations are both a challenge and an opportunity. Future developments are primarily related to changes in the provision of secondary building components.
Research limitations: The limitations of this study are that social practice theory was not applied to the entire research as it is not suitable for the assessment of challenges, opportunities, and potential future developments. A greater variety of circular material hubs, not in number but in their field of activity, could present a different view on the system. Semi-structured interviews also always have certain limitations. Identifying the practices while they are being performed could also have led to more in-depth results.
Originality/value: By providing a comprehensive view on the system of circular material hubs in the Netherlands, this research helps to understand the dynamics within the system and allows the identification of potential interventions based on the practices that constitute the system.

This paper examines the potential for privatising the port of St. Eustatius to achieve self-sustainability through the strategic port planning process. Design criteria were established based on a PESTEL, SWOT, and trend analysis, resulting in the development of four strategies. These strategies include enhancing port resilience, creating a transshipment hub, accommodating cruise ships, and enabling the docking of recreational vessels. Based on the strategies, opportunities for privatisation were identified according to the different rationales. Within the different strategies, opportunities for privatisation and a corresponding adaptation of the administrative model are possible. However, the need for large infrastructure investments could hinder the willingness of private parties to invest. Therefore, a public-private partnership is seen as a possible alternative to share the financial risks and also enable the government to retain control.

Inland waterway transport is a low CO2 emission alternative to road transport. A shift towards more inland waterway transport could also help reduce road congestion and noise pollution. Infrastructure bottlenecking, particularly at locks, is part of the reasons preventing this shift. Congestion is leading to delays. Locks can be physically improved, or the passage of the vessels through the locks can be optimized through scheduling. Recent work introduced a novel switching-max-plus-linear system approach to scheduling vessels passing through networks of waterways and locks, also introducing a novel routing component to the scheduling problem. Switching max-plus-linear systems are a convenient way to model scheduling systems using max-plus-linear algebra. The switching-max-plus-linear model only considered locks with a single chamber that can only process one vessel at a time. Additionally, it only considered four specific waterway network configurations, rather than any arbitrary network configuration. Real locks can have multiple chambers, and they can process multiple vessels at the same time if they are placed according to regulations in the two-dimensional space of the chamber. The scope of this report was then to build upon this switching max-plus-linear model by adding support for arbitrary network configurations, and multi-chamber, multi-vessel locks with proper twodimensional ship placement, to answer the main research question: How can multi-vessel, multichamber locks with ship placement be integrated into the SMPL IWT scheduling model? Three mathematical scheduling models formulated as SMPL systems were introduced, each subsequent model building on the previous one. The first introduced support for arbitrary network configurations. The second introduced support for multi-chamber locks and allowed vessels to pass through lock chambers at the same time, provided that their assigned one-dimensional sizes fit into the assigned one-dimensional capacity of the chamber. The third introduced support for twodimensional ship placement through a Tetris-like placement sequence also modeled as a switching max-plus-linear system. The models were translated to mixed integer linear programming models, and arrival time and arrival time offset objectives were added, so they could be used as the rules by which a scheduler would build and solve offline scheduling optimization models on a case-by-case basis. Auxiliary objectives to promote vessels slowing down, rather than waiting stationary in the waiting areas, were also added. The models were all found to be working as intended and implemented correctly through the use of a number of verification cases and tests. Complexity tests showed that the solution times for all three models already became larger than a practical limit of 15-20 minutes for simple scenarios with 10-15 vessels. A heuristic model that mimics how vessels are assigned to lockages in practice was built. Comparisons to the scheduling models on the verification cases showed negligible differences for the models in single-lock cases, but it indicated that the multi-vessel, multi-chamber models may outperform practice in multi-lock cases. Future research is recommended to focus on online optimization to account for disturbances, distributed optimization to reduce calculation times, and validation of the model’s performance with real data.

This master thesis focuses on the effect of variabilities in a Power & Free conveyor system on the flow continuity by an analysis on the product, process and production level (3P), a discrete-event simulation model and the theory of Cyber-Physical Production systems (CPPS) to control the product flow. Scenarios were evaluated with this model and the results show the effect of performance increase when variability decreases. Requirements are set to come to real-time control by developing this model into a digital twin as part of a CPPS. It can be concluded that the discreteevent model can be used to predict the performance and take control measures accordingly, subsequently real-time control is possible by implementing real-time sensor measurements in the model, thereby developing the model into a digital twin.

In this day and age sustainability is becoming increasingly important. Even though the airline business is not the first thing which comes to mind when regarding sustainability there are huge efforts in play to extend the life of airplanes and its corresponding components. This is done via remanufacturing. Remanufacturing can here be defined as:” Returning a used product to at least its original performance with a warranty that is equivalent to or better than that of the newly manufactured product” (Gunasekara, et al., 2018). Even though numerous attempts using traditional techniques like Lean have been tried at KLM E&M, none have yielded the long term desired results, which is why a different approach is needed. Remanufacturing brings numerous problems with it, unknown to traditional manufacturing (Guide Jr & Daniel, 2000). These problems result in the operational level of the organisation not having control over the process, which leads to subpar performances. Furthermore, a gap originates between higher level management and the operations, which leaves a lot of potential uncovered as well as discourage operational level progress. The proposed model is designed to help gain control over an uncontrolled process, improve its performance and sustain the newly found control, which is also the purpose of this research. This is all achieved using a more bottom-up integral approach. This proposed model is combined with the operational lean maturity model developed by Maasouman (Maasouman, 2015), in order to create a Remanufacturing Process maturity model, which indicates the maturity level of each aspect used in the Remanufacturing Process control model, resulting in a model which has both quantitative and qualitative aspects.

There is an ongoing trend of urbanisation, and cities are becoming more and more crowded. In 2014, 46\% of the population of the OECD countries lived in urban areas. Whereas the growth of cities was previously mainly an expansion, the growing population is now increasingly leading to densification. Since 2007, more than half of the constructed houses in the Netherlands has been placed within the existing built area. In the most recent period (2016 to 2018), the share even was 56 per cent. There is a controversy between the individual desire to have a car and the contrasting desire to remove cars from the outdoor space in inner cities. Moreover, land-use policies positively contribute to the environment by managing car use and improving accessibility. Identifying success and failure factors regarding the used strategy and implementation provides feedback to evaluate the strategy. The hub can combine different aspects of mobility, help remove cars from the streets, promote car-sharing and electric vehicles and therefore be an important part of the solution. However, the set-up and implementation of a mobility hub is a complex endeavour where many stakeholders are involved, and sound policy is crucial. In the structured search performed to identify success and failure factors of mobility hubs, an important finding was that the literature is heterogeneous. The gaps found between theory and practice concern the financial feasibility, the incentives for alternative transport, good relationships and clear responsibilities of stakeholders and attention for increasing the utilisation rates of transport modes. Concerning the barriers, competing goals of modal shift and EV adoption need attention, and again, stakeholder responsibilities were not completely clear.

This research explored potential designs of an innovative mitigation strategy to combat the aircraft-produced ultrafine particle (UFP) concentrations at Amsterdam Airport Schiphol (AMS). This technique is based on the principle that fine water droplets are able to encapsulate dust and fine particles, which clump together and eventually descent to the ground. The reduction of airborne particle concentrations is expected to have a significant effect on the health of (platform) employees, which makes it an interesting strategy to further investigate. A wide variety of stakeholders, from both the aviation industry and the academic world, were interviewed about the important design components that need to be incorporated in a potential mitigation system, as well as essential requirements that the system needs to comply with. A system that integrated the cold start of the aircraft engines as the most suitable moment and the introduction of remote starting positions as the most optimal location for the implementation of UFP mitigation strategies, contributed to the proposed conceptual design for AMS. A system alternative in which the water droplets are directed into the jet engine outlets by spraying cannons was discussed for a close-up mitigation strategy, while an alternative in which a screen of water droplets is created to absorb the jet blast with emissions was established for the mitigation strategy at a further distance. The assessment of the conceptual system design, on its feasibility, viability and desirability, showed that the UFP mitigation system could have a desirable impact on Schiphol’s environment on the short-term. However, the possibilities of implementing remote starting positions at AMS and the impact that the system has on the starting capacity and the turnaround time should be further investigated to increase the system’s feasibility and viability.

Quay cranes on modern container terminals have the possibility to lift two 40ft. containers side by side. In order to be able to perform this type of lift, the crane must be equipped with a tandem spreader. As this type of spreader cannot be used for performing certain lifts, such as the handling of hatch covers, switches between single spreader and tandem spreader are inevitable. However, there is no method in current literature nor in practice to determine when the spreader changes should be performed. Therefore, the aim of this research is to develop a model that calculates the optimal moments to switch spreaders. As the performance of tandem lifting depends on the cycle times, a cycle time prediction model is developed first. This Artificial Neural Network model predicts the cycle time based on the type of lift, the actual position of the container(s) on the ship, the weight of the load and the current wind speed. The predictions yield a Mean Absolute Percentage Error of less than 11%. Afterwards, the cycle time prediction model is used to develop an optimal spreader switching strategy model in the form of a Mixed Integer Linear Programming model. A case study, in which several different bay layouts of a container ship need to be handled, shows a decrease in handling time of up to 22% compared to the traditional spreader switching strategy.

This study aims to develop a decision support tool which enables shipowners to select the most appropriate alternative fuel technology to comply with possible different imposed emission regulations while ensuring optimal business performance. In this context, most appropriate is defined as a fuel alternative which minimises required freight rate (RFR) while maximising overall performance on technological, environmental and other criteria. A decision support tool was devised combining a decision model based on the simple multi-attribute rating technique (SMART) with a financial model based on discounted cash-flow (DCF). Additionally, an optimisation model was implemented to optimise for minimal required freight rate through slow steaming. The decision tool provides shipowners with a quantified impact on their current business if they do not transition to alternative fuels under a 'market based measure' (MBM) regulatory scenario, as well as best-alternatives if their current fuels do not meet regulations under an 'emission cap' (EC) scenario. The decision tool is evaluated under optimistic, average and pessimistic scenarios in 2020, 2030 and 2050. Under an emission cap scenario, the results showed an overall preference for Fischer-Tropsch diesel (FTD) as the most promising alternative maritime fuel both in terms of SMART performance and required freight rate, followed by upgraded bio-oil (UBO). Nevertheless, the average difference in required freight rate of alternative fuels compared to HFO remains substantial, at 43% and 38% higher for Fischer-Tropsch diesel under a 'no regulation' scenario and 'market based measures' scenario, respectively. It is therefore evident that without regulatory intervention, heavy fuel oil is expected to retain dominance based on cost. Even under a market based measure (MBM) scenario, the average required freight rate of HFO increases only by 3.4% overall. For LNG, market-based measures lead to an average increase in RFR of 4.1%. These results suggest that in order for the maritime industry to transition towards sustainable alternative fuels, policymakers, governments, international organisations and lenders need to align their policies to collectively enable a more sustainable shipping industry - not only by enforcing stricter regulations, but also by providing the correct financial incentives.

With the increasing focus on project planning in engineer-to-order(ETO) companies, tracking the progress of the design phase of a project is essential for effective planning. Such progress tracking currently is done through the regular feedback of discipline leads, which are intrinsically subjective. The information thus collected is then plotted in the form of so-called S-curves, to represent the progress over the course of the project. The present method tracks progress of the manufacturing engineering phase based on how much mass is designed with respect to the design weight of the equipment. This so-called mass curves are used and fitted to an S-curve and represent the tracked progress. It is shown that the fitted mass curves represent the progress of the engineering phase with a systematic average error of 25 days. Additionally, mass data retrieved from completed projects are used to predict the S-curves shape of the ongoing project. The weighted average of tracked and Predicted S-curves is then used in a Monte Carlo simulation in order to estimate the progress of the ongoing project. The method was found to have a tracking accuracy of 0:6 4%, which translates into an uncertainty on the project duration and therefore on the equipment delivery date, by 2 weeks. This uncertainty is found to be the upper bound of typical grace periods agreed with most clients. The present results might offer a new outlook on progress tracking on the progress tracking of manufacturing engineering activities. Further research shall be conducted to address the progress of earlier engineering phases equally.

In order to keep the hydraulic infrastructure system in the Netherlands from deteriorating, large investments will have to be done in the near future. Decision-support frameworks help in making the right investment decisions for infrastructure that is intended to stand for a hundred years. Such a long lifetime brings forth a high level of uncertainty, regarding climate change as well as its impact on interdependence. So far, most of the adaptive decision-support
frameworks do look at climate change uncertainty, but do not consider interdependence as a distinctive factor between design alternatives. This research presents a first impulse to incorporate climate change uncertainty and interdependence into the decision-making process. Under the scope of a case study, the renewal of a pumping station, relevant interdependencies are identified. Next to the original design alternatives, new design alternatives are created based on the theory of Adaptivity, Engineering Options and Modularity. The influence of the alternatives on the interdependencies is assessed, and their life cycle costs are calculated. The findings are presented in a proposal for a decision-support framework. This research shows that incorporating interdependence and climate change uncertainty makes inherently flexible design alternatives more desirable than static design alternatives. For the identified interdependencies, the adaptive design alternatives have a more positive effect. Also, the costs of the adaptive design alternatives are continuously lower than the static design alternatives.

Planning the on-site transportation of large manufacturing sites is a complex process. Currently these plans are made based on the on-site logistics constraints rather than on KPIs. Research has been focused on either analysis of system parameters or generally on KPIs, but lacks the combination of both on real-life cases. This gap is closed by taking both system analysis and KPI development into account to develop a working planning tool that can assist planners in a real-life situation. The goal of this study is to gain insights in the on-site transportation planning of large manufacturing plants and their performance measurement. This study answers the question: How can the on-site transportation planning at a large manufacturing plant be improved, by 1.) adding company KPIs and 2.) data-driven decision support based on the parameters of the locality and its constraints? Through the application of the DMADE methodology, this research question is answered. The SCOR performance measurement framework is used to determine the KPIs of the on-site transportation plans. A planning model, classified as a Resource-Constrained Multi-Project Scheduling problem, is formulated as a Mixed-Integer Linear Program. This planning model optimizes the on-site transportation plans for the KPIs, proves the correctness of the KPIs and shows the potential performance increase of on-site transportation plans if constructed by the planning model.

This research focuses on identifying and evaluating ways to improve the sustainability of solid waste management (SWM) in semi-public spaces using the Efteling theme park as a case study. To the best of the author’s knowledge, this study is the first to apply an integrated waste management approach to optimize SWM in this context. The approach consists of assessing the integrated environmental and economic burdens of the collection, transportation, sorting and treatment processes of a SWMstrategy. Approximately 10 alternative high potential SWM strategies were composed and selected out of a very large pool of possible SWM strategies. The environmental and economic impact of these high potential SWM strategies for the Efteling case was subsequently assessed using the WARM LCA model and a custom economic assessment model. The results reveal that emission reductions of up to 190 ton CO2 equivalents (TCO2E’s) per year, relative to the current strategy, can already be achieved by separating and recycling more fractions from behind-the-scenes (BTS) waste. This corresponds to an increase in yearly avoided SWM system emissions of about 25% for the Efteling case (from a life-cycle perspective). When public/semi-public (PSP) waste is also included, emission reductions of up to 800 TCO2E’s per year can be achieved for single-fraction separation (e.g. PMD or PET) and up to 960 TCO2E’s per year for two-fraction separation (e.g. PMD + paper or PMD + cups). This corresponds to major increases in avoided SWM system emissions of 110% and 131% respectively. It was also found that small interventions in the transport and/or treatment waste management components can make a big difference in the environmental and/or economic impact of a SWM strategy. A majority of the alternative SWM strategies has an eco-efficiency (emission reduction cost-effectiveness) ranging from €39 to about €140 per TCO2E saving. This eco-efficiency is (much) higher than that of a range of benchmarks such as the eco-efficiency of solar-pv panels at a non-industrial scale, wind turbines at sea and the eco-efficiency of office building insulation. This indicates that optimizing waste management should be given more priority in (scientific) research as well as in practice.

An increasingly dynamic and competitive market forces MRO businesses to improve on efficiency and sustainability of remanufacturing processes. Present research focus on current process states and recovery, improvement and control of process phases beyond initial design without inclusion of return quality. This research addresses a method for sustainable initial repair process design from a return quality perspective. For this purpose it introduces a return quality control model that provides repair process design guidelines. The aim of the research is to provide a foundation for automated repair process design that incorporates future states and the relation of return quality to the operational process.

Since 2011, an electronic registration system, called the OV chip card, has been in use in the Netherlands for the payment of all public transport. As a result, the Dutch Railways (NS) have implemented all the necessary equipment to support the sales and validation processes of this system. Another company (Thales, the agent) has been hired to maintain all these resources on behalf of NS (the principal). In this paper, qualitative and quantitative research into the current maintenance process has been carried out. This research shows that various inefficiencies occur in the current maintenance process. The most important ones are unnecessary process steps for the mechanic at Thales, multiple Work Order Tasks to solve single incidents and the difficulty to plan efficiently due to the many fatal failures. Additionally, this study shows that collaboration between the principal and the agent is an essential factor which can undermine efficiency. An important example of inefficiency due to poor collaboration is the occurrence of repeated failures. This is caused by a lack of transparency on past maintenance of particular resources. In this case study, four crucial improvement directions are identified. In no particular order, these are a different maintenance strategy, the prevention of unnecessary and repeated processes, transparency in data and demand-driven failure prioritisation. Generalisation of this research is difficult, but this study shows that in complex maintenance situations problems can be solved with both technical and procedural adjustments, as well as by improved cooperation between the party that commissioned the maintenance and the party who then performs the maintenance.

Due to the global climate change there is a increasing demand for transportation on renewable fuels. An increasing trend in electric propulsion can already be seen in the automotive industry and this is now also gaining popularity in the maritime sector. Due to limited capacity if the onboard battery, especially electric ferries are becoming more popular, because of the relative short sailing distances. The first electric ferry became operational in 2015 in Norway and since than a hand full of electric vessels was developed. An electric vessel requires a charging mechanism to charge while unloading and loading passengers in the port. Besides, generally also a mooring mechanism is necessary. This enables the vessel to turn off the propeller while charging which limits the energy demand while charging. Various systems have been developed already. However, these are not standardized solutions but all one of a kind systems designed for a specific vessel or fleet. Which of these is the best solution is not easy to determine and strongly depends on the vessel characteristics and the operating environment. To supply the expected increasing demand for electric vessels, a guideline is developed which will help the engineer to find a suitable charging and mooring mechanism and to decrease the selection time for this system. The will provide Damen a strategic advantage towards other shipyards in vessel tenders since both the development costs and delivery time is lower.
This guideline is developed based on the knowledge gained during a case study for a 81m Ropax ferry, sailing in the surroundings of Vancouver Island. For the case study an engineering design method was selected from literature and applied to this case, for which Damen had a hard time finding a charging and mooring mechanism. First thought was to combine both into one mechanism, but this is difficult due to conflicting functionalities of both systems. Due to the limited time available for the research, the design of the mooring mechanism is not taken into account for the case study. Setting the requirements for the charging mechanism is complex due to the range of different fields of interest that should be taken into account. However, the requirements of these various aspects are often related in some way to one another. This makes it easy to lose sight of the structure of all requirements. Comparing the functions that the charging mechanism should fulfill within these requirements and the existing charging mechanisms, it can be concluded that no suitable system is available yet. The gap between these is defined as a set of three functions; to compensate the tidal difference, deal with misalignments between the vessel and the shore and to provide flexibility for vessel motions. A new design was made which covers this gap. Additional research was done to ensure sufficient flexibility from the power cable, since this proved to be critical in the state of the art systems.
From the knowledge gained during this case study, the guideline is developed. The guideline provides insight in the influential factors while selecting an mechanism. This should offer the engineer a structure to set the requirements and ensures that no aspect is left out of the requirements. An overview with the already existing mechanisms is provided which should be consulted multiple times during the process, to check whether a suitable systems exist, if the requirements should are too tight or if the project is not profitable at all. The structure of the requirements is designed such, that the relative easy requirements are set first. This prevents from doing demanding calculations or going on expensive business trips, while it could have been seen earlier that a project is not feasible or profitable at least. The guideline is validated while selecting a charging mechanism for a different type of vessel. This validation proved to decrease the selection time for a charging mechanism significantly compared to previous projects within Damen. After the test, a charging system was found which is preferred for the vessel. This charger is now further discussed with the supplier of the system.

In-plant transport systems are indispensable in facilities like manufacturing plants and warehouses as they enable the internal flow of goods. Facilities in the Maintenance Repair & Overhaul industry are no exception to this, but face some distinct challenges. This research presents an integrated approach to the conceptual design of an in-plant transport system for an MRO facility in the aerospace industry. The integrated approach distinguishes conceptual design as a separate phase and structures design efforts within this phase using the Define, Measure, Analyze, Design, Evaluate (DMADE) cycle. One major iteration through this cycle is done for a real-life case system at an MRO facility for aircraft components. After an exploratory literature survey, demand for the case is analyzed using enhanced Value Stream Mapping (denoted as VSM-Information) and data analysis. Design requirements and decision criteria are established that determine the effectiveness of an in-plant transport system.Here, a fundamental trade-off is shown to exist in Transport Lead Time and capacity. Three Service Level targets are set for the case to make this trade-off in design. A generic Design Interactions Framework for (vehicle-based) in-plant transport systems is proposed that addresses a lack of guidance in literature on forming integral designs during synthesis. The framework is applied to the case to compose three integral alternatives in which both call systems with Automated) Guided Vehicles and in-plant milk-runs are used. The logistic performance of the design alternatives is reviewed using Discrete Event Simulation. Minimum Viable Configurations (MVCs) are derived that state the minimum amount of transport resources per design alternative per Service Level target. Cost estimation and implementation risk assessment are performed for the MVCs found. Multi-Criteria Decision Analysis is applied using the Weighted Sum Method to establish a preference ranking for the MVCs. The robustness of this ranking is assessed using a scenario-based sensitivity analysis. Results show that four MVCs exist for the design alternatives and Service Level targets defined. Two of these MVCs compete for the first place in the preference ranking and hence no clear preferred alternative is identified for the case. The ranking between the top-two MVCs is highly sensitive to setting the weight factors in the WSM. It turns out that their effectiveness highly depends on the monetary implications of a certain TLT performance and implementation risk; which couldnot be quantified in this research due to time restrictions and data unavailability. Although the results of the case study are highly case-specific, the approach taken, design principles derived and tools used are widely applicable in the design of effective in-plant transport systems and show the specific characteristics of these systems in an MRO context.

Due to complex nature of aircraft heavy maintenance checks, achieving process stability is difficult. Literature suggests that this stability can be obtained by separating routine and non-routine work, and focusing on quick identification of non-routine tasks by completing inspection tasks early in the check. Current task planning methods show limitations in producing a feasible task planning, motivating the need for an advanced task planning model. This model combines the task elements of manpower, work order, and aircraft zone to find the minimum TAT given the task complexity-based heuristic. For this model, aircraft zones have been redefined, as the zones specified by Boeing are not suitable for task planning. An experiment using the advanced task planning model is conducted for the Inspection Phase tasks of the Boeing 777 C07 check. The target is to complete all tasks in 48 hours. Results show that it is feasible to perform all Inspection Phase tasks in 61.28 hours, where 99.51% of the tasks is completed in 48 hours. Completing all tasks takes 8 shifts, with a maximum of 31 technicians in a shift. The total TAT can be further reduced by identifying and lifting the constraints in the planning. One example shows how this can lead to an 8 hour reduction in total TAT for the best experiment scenario, bringing the TAT closer to the 48-hour goal. This demonstrates how the advanced task planning method can be used to stabilise aircraft heavy maintenance.

This thesis addresses a problem at KLM E&M, where a gap exist between the desired performance and current performance of airframe MRO. This research is performed to find solutions within the A-check for wide body aircraft by identifying the constraint in the A-check and subsequently develop solution alternatives by first exploiting the constraint, then elevating and finally develop a ‘desired world’ alternative. For the A-check a theoretical preliminary model was developed which tests Phase-Gate methodology and concentrating resources within the phases during the check. It was found that applying Phase-Gate and aligning the available manpower to the workload could improve the output performance of the A-check. The best of the designed solution alternatives all consists an implementation of a core shift, which focus of aligning and full concentration of available manpower to the workload.