The Application of Material Requirements Planning (MRP) System to Aircraft Parts Inventory

As the title implies, the application of MRP into an aviation context is the response to the huge cost of parts holding in an ever-expanding industry. The nature of intermittent parts demand (unpredictable parts), typical of maintenance and overhaul inventory parts control, is investigated both to illustrate the deficiency of traditional ROP systems for dependent-demand inventory and other applications in the area of lot sizing and forecasting with a specific exploration into sources of demand lumpiness. In order to investigate current inventory procedure, we surveyed 175 airline operators and maintenance service organisations, to explore the status of MRP and ROP worldwide. This response showed current inventory practice to be less than effective and that better systems were required, leading us to investigate specific problems experienced namely; lot-size and forecasting methods used within the MRP concept. MRP had made some inroads into the aviation sector, but a number of factors have prevented its general uptake. Through a case study of KTM-uk’s workshop practices within overhaul and repair, we apply various solutions to lot-size and forecasting methodology in order to realise best practice, putting forward a small scale MRP-spreadsheet as a working tool. In the process we present two predictive models; a Lot-size Predictive Cost Model. LPCM, and a Predictive Error-Forecasting Model, PEFM. The models in their present form use seventeen lot-size and thirteen forecasting methods respectively, simplifying material management through appropriate estimates of costs and planning needs. Within lotsizing, we found that under almost all operations conditions the WWA and MSM2 methods give the best performance. Similarly the WMA method followed by the Holt and the Croston methods work best for forecasting intermittent demand parts

Forecast Combination

Actualmente existen diversas metodologías de pronóstico, que van desde el conocimiento empírico hasta métodos innovadores, individuales o combinados, que demuestran resultados óptimos. Este documento se deriva de un proceso de investigación y presenta alternativas relacionadas con las combinaciones de pronósticos, utilizando metaheurísticas, por ejemplo, mediante la búsqueda tabú y la programación evolutiva para optimizar el pronóstico. El documento presenta pronósticos combinados basados en la programación evolutiva utilizando mezclas de modelos de regresión bayesiana y modelos de regresión lineal clásico, el modelo de media móvil integrado autorregresivo, el suavizado exponencial y la regresión bayesiana. El documento presenta dos artículos derivados de investigación, la primera compara el algoritmo combinado con los resultados individuales de estos modelos individuales y con la combinación de Bates y Granger utilizando un indicador de error y el valor simétrico de error absoluto medio. Esos modelos y la combinación se aplicaron a la simulación de series temporales y a un caso real de ventas de productos lácteos, generando así pronósticos combinados multiproductos tanto para la simulación como para el caso real. La nueva combinación combinada con la metaheurística evolutiva mostró mejores resultados que los de los otros que se utilizaron. La segunda investigación utiliza series de tiempo simuladas, diseñando dos metaheurísticas basadas en la lista Tabú, que aprenden de los datos con base en el comportamiento estadístico de éstos, como el cluster, así como del mismo valor optimizado del error de ajuste, y se comparan las combinaciones de pronósticos con resultados de modelos individuales a tres tipos de series de tiempo.Currently diverse forecasting methodologies exists, going from the empirical knowledge to the innovative methods, individual or combined, demonstrating optimal results. This document is derived from a research process, and presents alternatives related to forecast combinations, using metaheuristics, for example, by using Tabu search and Evolutive programing to optimize forecasting. One of the designed process consists of creating combination forecasts based on evolutionary programming using, first, a mixture of Bayesian regression models and, second, a mixture of the classical linear regression model, the autoregressive integrated moving average model, exponential smoothing and Bayesian regression. The first research compares the novel combined algorithm with the individual results of these individual models and with the Bates and Granger combination using an error indicator and the symmetrical mean absolute error value. Those models and the novel design were applied to time series simulation and to a real case of dairy products sales, thus generating multiproduct combination forecasts for both the simulation and the real case. The novel combination combined with the evolutionary metaheuristic showed better results than those of the others that were used. The second research uses simulated time series and other metaheuristic that learns from the data an statistical behavior.Tecnológico de Antioquia, Universidad Nacional de Colombia.Doctorad

Improving Logistics Processes in a Global Spares Supply Organization

This thesis studies logistics processes related to balancing of the inventories between supply channels. Balancing operations are based on lateral transshipments, which are a recent field of studies and have been on the focus of the optimization studies during the past few years. The findings of the study model current processes and material flows, reveals issues related to processes, studies cost figures and provides alternative solutions for improvement. The main objective of the study is to provide a construction that makes it possible to improve decision-making related to inventory balancing between the distribution centers of the organization. This study answers three main questions: How does the existing inventory network look like? What kind of issues and development areas are there? How is it possible to improve current inventory pooling operations? This study is a single case study carried out in a global spares supply organization willing to improve their logistics processes. To achieve the objects of the study, several methods were needed: literature survey on logistics models, sourcing methods and logistics cost models, qualitative information through interviews in the case company, study of the existing process descriptions and contract terms in addition to several quantitative analyses on the performance of the operations. Due to multiple methods, reliability and validity is increased as is the extent of the study. Findings of this study demonstrate that the expansion of the company on Asian markets is in its infancy and that the processes lack standardization and appropriate tools. Asian Distribution Center is highly dependent on European suppliers. Despite the strategic aspect of Asian supplier markets, supplier base does not yet provide a comprehensive alternative for balancing transshipments from Europe. This underlines the importance of processes on inventory balancing as they provide significant cost reductions against local sourcing in Asia at the moment. It is recommended to continue balancing using European supply chains, but to set up ocean deliveries for major flows and to focus sourcing efforts on establishing local suppliers for materials that have the highest importance by their total value. Future studies should provide more detailed information on quality and sourcing related costs to improve cost analysis and comparisons in addition to benchmarking values and ratios. /Kir1

Improving complex enterprises with system models

Thesis (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division, 2005.Includes bibliographical references (leaves 96-98).Air Force sustainment operations are the focus of an intensive internal effort to improve performance and reduce costs. Past improvement initiatives have often failed to produce the intended results, and have caused performance to decline in some cases. Exploratory research was conducted at an Air Logistics Center to study how improvements are executed. Two conclusions are drawn from this research. The first is that changing sustainment operations is a problem of high dynamic and behavioral complexity. The second conclusion is that system models are well suited to coordinating change at the ALC because they provide insight into how a complicated system can be managed and improved. Three key findings support these conclusions. First, there is significant correlation between categories of unavailable F-16 aircraft such that reductions in one category are associated with increases in another. Second, an analysis of change efforts in two parts of the ALC shows that systemic influences, such as the inability to reinvest in improvements, are hindering change initiatives in one part of the ALC.(cont.) The third finding is that a model of sustainment operations suggests that independent improvement initiatives are outperformed by coordinated efforts driven with an understanding of systemic interactions. Leaders throughout the sustainment community have expressed their desire to understand how sustainment operations function as a system. A hybrid approach to change is offered as a method for understanding and improving sustainment operations. System models are used to quantify and model system interactions; then policies and recommendations are drawn from the models. Recommendations may include process-level improvements utilizing change methods already in use at the ALC.by Justin M. Hemann.S.M

Розробка підсистеми прогнозування системи управління маркетинговою інформацією на промисловому підприємстві

The theoretical generalization, which is revealed in the development of conceptual and methodological principles and methodical provisions related to formation and functioning of the forecasting subsystem of the marketing information management system at an industrial enterprise, is presented.The market is a social phenomenon in which the availability of valuable marketing information reduces uncertainty, ensures the promptness of making managerial decisions, makes possible to avoid threats and creates a basis for increase in the efficiency of a production process and competitiveness. Therefore, the control of changes in the marketing environment requires the creation of a marketing information management system at an industrial enterprise, which is based on effective methods of collection and analysis of marketing information. Markets of industrial enterprises make possible to create and test progressive marketing information management systems.There are trends that cause worsening of prospects for economic growth at the current state of the marketing environment of industrial enterprises. Growth of these risks is facilitated by trends of globalization, informatization, social changes. Such an increase in business risks causes an increase of the role of forecasting. The classical concept of a marketing information management is enhanced and system is restructured and the creation of a subsystem of forecasting is improved. The methodological approach to the functioning of forecasting subsystems of marketing information systems of industrial enterprises based on the model of statistical forecasting of sales volume is offered.The proposed procedure to overcome a general lack of forecasting methods is related to the failure to take into account an inaccuracy of observations on which the forecast is based, – it is based on the use of fuzzy mathematical methods. It is shown on its basis how traditional forecasting methods can be successfully upgraded for the case when the initial data are given unclearlyИсследованы тенденции развития промышленных рынков и состояние научной мысли относительно определения понятия «система управления маркетинговой информацией». Установлена необходимость модернизации классической концепции построения системы управления маркетинговой информацией промышленного предприятия. Разработаны классификация информации, поступающей в подсистему прогнозирования и типы прогнозов, которые могут быть получены в подсистеме прогнозирования системы управления маркетинговой информацией промышленного предприятияДосліджено тенденції розвитку промислових ринків та стан наукової думки щодо визначення поняття «система управління маркетинговою інформацією». Встановлено необхідність модернізації класичної концепції побудови системи управління маркетинговою інформацією промислового підприємства. Розроблені класифікація інформації, яка надходить у підсистему прогнозування та типів прогнозів, які можуть бути отримані в підсистемі прогнозування системи управління маркетинговою інформацією промислового підприємств

An integrated approach to value chain analysis of end of life aircraft treatment

Dans cette thèse, on propose une approche holistique pour l’analyse, la modélisation et l’optimisation des performances de la chaîne de valeur pour le traitement des avions en fin de vie (FdV). Les recherches réalisées ont débouché sur onze importantes contributions. Dans la première contribution, on traite du contexte, de la complexité, de la diversité et des défis du recyclage d’avions en FdV. La seconde contribution traite du problème de la prédiction du nombre de retraits d’avions et propose une approche intégrée pour l’estimation de ce nombre de retraits. Le troisième et le quatrième articles visent à identifier les parties prenantes, les valeurs perçues par chaque partenaire et indiquent comment cette valeur peut affecter les décisions au stade de la conception. Les considérations relatives à la conception et à la fabrication ont donné lieu à quatre contributions importantes. La cinquième contribution traite des défis et opportunités pouvant résulter de l’application des concepts de la chaîne logistique verte, pour les manufacturiers d’avions. Dans la sixième contribution, un outil d’aide à la décision a été développé pour choisir la stratégie verte qui optimise les performances globales de de toute la chaîne de valeur en tenant compte des priorités et contraintes de chaque partenaire. Dans la septième contribution, un modèle mathématique est proposé pour analyser le choix stratégique des manufacturiers en réponse aux directives en matière de FdV de produits comme le résultat des interactions des compétiteurs dans le marché. La huitième contribution porte sur les travaux réalisés dans le cadre d’un stage chez le constructeur d’avions, Bombardier. Cette dernière traite de l’apport de « l’analyse du cycle de vie » au stade de la conception d’avions. La neuvième contribution introduit une méthodologie d’analyse de la chaîne de valeur dans un contexte de développement durable. Finalement, les dixième et onzième contributions proposent une approche holistique pour le traitement des avions en FdV en intégrant les concepts du « lean », du développement durable et des contraintes et opportunités inhérentes à la mondialisation des affaires. Un modèle d’optimisation intégrant les modèles d’affaires, les stratégies de désassemblage et les structures du réseau qui influencent l’efficacité, la stabilité et l’agilité du réseau de récupération est proposé. Les données requises pour exploiter le modèle sont indiquées dans l’article. Mots-clés: Fin de vie des avions, analyse de la chaîne de valeurs, développement durable, intervenants.The number of aircrafts at the end of life (EOL) is continuously increasing. Dealing with retired aircrafts considering the environmental, social and economic impacts is becoming an emerging problem in the aviation industry in near future. This thesis seeks to develop a holistic approach in order to analyze the value chain of EOL aircraft treatment in the context of sustainable development. The performed researches have led to eleven main contributions. In the first contribution, the complexity and diversity of the EOL aircraft recycling including the challenges and problem context are discussed. The second contribution addresses the challenges for estimation of retired aircrafts and proposes an integrated approach for prediction of EOL aircrafts. The third and fourth contributions aim to identify the players involved in EOL recycling context, values perceived by different shareholders and formulate that how such value can affect design decisions. Design stage consideration and manufacture’s issues are discussed and have led to four main contributions. The fifth contribution addresses the opportunities and challenges of applying green supply chain for aircraft manufacturers. In the sixth contribution, a decision tool is developed to aid manufactures in early stage of design for their green strategy choices. In the seventh contribution, a mathematical model is developed in order to analyze the strategic choice of manufacturers in response to EOL directives as the result of the interaction of competitors in the market. An internship project has been also performed in Bombardier and led to the eighth contribution, which addresses life cycle approach and incorporating the sustainability in early stage of design of aircraft. The ninth contribution introduces a methodology for analyzing the value chain in the context of sustainable development. Finally, the tenth and eleventh contributions propose a holistic approach to EOL aircraft treatment considering lean principals, sustainable development, and global business environment. An optimization model is developed to support decision making in both strategic and managerial level. The analytical approaches, decision tools and step by step guidelines proposed in this thesis will aid decision makers to identify appropriate strategies for the EOL aircraft treatment in the sustainable development context. Keywords: End of life aircraft, value chain analysis, sustainable development, stakeholders

Design and Simulation of RFID-Enabled Aircraft Reverse Logistics Network via Agent-Based Modeling

Reverse Logistics (RL) has become increasingly popular in different industries especially aerospace industry over the past decade due to the fact that RL can be a profitable and sustainable business strategy for many organizations. However, executing and fulfilling an efficient recovery network needs constructing appropriate logistics system for flows of new, used, and recovered products. On the other hand, successful RL network requires a reliable monitoring and control system. A key factor for the success and effectiveness of RL system is to conduct real-time monitoring system such as radio frequency identification (RFID) technology. The RFID system can evaluate and analyze RL performance timely so that in the case of deviation in any areas of RL, the appropriate corrective actions can be taken in a quick manner. An automated data capturing system like RFID and computer simulation techniques such as agent-based (AB), system dynamic (SD) and discrete event (DE) provide a reliable platform for effective RL tracking and control, as they can respectively decrease the time needed to obtain data and simulate various scenarios for suitable best corrective actions. The functionality of the RL system can be noticeably elevated by integrating these two systems and techniques. Besides, each computer simulation approach has its own benefits for understanding the RL network from different aspects. Therefore, in this study, after designing and constructing the RL system through the real case study from Bell Helicopter Company with the aid of unified modeling language (UML), three simulation techniques were proposed for the model. Afterwards the results of all three simulation approaches (AB, SD and DE) were compared with considering two scenarios of RL RFID-enabled and RL without RFID. The computer simulation models were developed using “AnyLogic 7.1” software. The results of the research present that with exploiting RFID technology, the total disassembly time of a single helicopter was decreased. The comparison of all three simulation methods was performed as well. Keywords: Reverse logistics (RL), RFID, aerospace industry, agent-based simulation, system dynamic simulation, discrete event simulation, AnyLogi