Data-driven prognostic method based on Bayesian approaches for direct remaining useful life prediction.

International audienceReliability of prognostics and health management systems (PHM) relies upon accurate understanding of critical components' degradation process to predict the remaining useful life (RUL). Traditionally, degradation process is represented in the form of data or expert models. Such models require extensive experimentation and verification that are not always feasible. Another approach that builds up knowledge about the system degradation over the time from component sensor data is known as data driven. Data driven models, however, require that sufficient historical data have been collected. In this paper, a two phases data driven method for RUL prediction is presented. In the offline phase, the proposed method builds on finding variables that contain information about the degradation behavior using unsupervised variable selection method. Different health indicators (HI) are constructed from the selected variables, which represent the degradation as a function of time, and saved in the offline database as reference models. In the online phase, the method finds the most similar offline health indicator, to the online health indicator, using k-nearest neighbors (k-NN) classifier to use it as a RUL predictor. The method finally estimates the degradation state using discrete Bayesian filter. The method is verified using battery and turbofan engine degradation simulation data acquired from NASA data repository. The results show the effectiveness of the method in predicting the RUL for both applications

Workforce planning for practical training programs via multi-criteria decision making

Sektörde eğitim ve takiben yapılan işe alım programları, turizm ve diğer hizmet odaklı sektörler için verilen eğitimlerin özünü oluşturmaktadır. Ancak bu programlar belirli süreler aldığı için katılım yapan öğrenci/yeni mezunlar bir başlangıç yaptıktan sonra çeşitli sebeplerle programdan ayrılarak sonunu getirmeyebilmektedir. Belirli bir işgücü yaratan bu öğrencilerin ani ayrılışları eğitimin verildiği kurumun işgücüne de zarar verebilmekte olup, kurum yöneticilerinin sektörde eğitim programları için öğrenci alım kararlarını verirken planlı olmayan öğrenci kayıp unsurunu da dikkate almaları gerekmektedir. Bu çalışmada hizmet odaklı bir sektörde, ilgili bölümlerin mezunlarının katıldığı iki aşamalı özel bir eğitim programı için bir optimizasyon modeli oluşturulması hedeflenmiştir. İlgili kurumdaki yöneticiler hangi bölümden kaç tane yeni mezunu programa katacaklarına, planlı olmayan ayrılmalar ve işgücü kapasitesi kısıtlarını da göze alarak karar vermek durumundadır. Problemin çözümü için çok ölçütlü karar verme yöntemlerinden hedef programlama tekniğini kullanılmış ve sonuçlar analiz edilerek insan kaynakları yöneticileri için öngörüler elde edilmesi amaçlanmıştır.Practical training programs constitute the essence of education for tourism and other service-oriented sectors. However, these programs take considerable time to finish, and participating students/new graduates may leave the program for a variety of reasons without finishing. Attrition can harm the overall workforce of the related institution, and it is necessary for the managers to take this factor into consideration for recruitment of these programs. In this study, it was aimed to establish an optimization model for a two-stage practical education program in which the recruits are new graduates of related departments aiming to work in a service-oriented sector. Managers in the relevant institution must decide how many new graduates to add to the program, planning for the attrition and labor capacity constraints. The goal programming technique was used for the solution of the problem and it was aimed to obtain managerial insights for the human resources management policies.No sponso

Agent-based material transportation scheduling of AGV systems and its manufacturing applications

制度:新 ; 報告番号:甲3743号 ; 学位の種類:博士(工学) ; 授与年月日:2012/9/10 ; 早大学位記番号:新6114Waseda Universit

When costs from being a constraint become a driver for concept generation

Managing innovation requires solving issues related to the internal development and engineering processes of a company (supply side), in addition to facing the market and competition (demand side). In this context, the product development process is crucial, as different tradeoffs and issues that require managerial attention tend to arise. The main challenges result in managers requiring practical support tools that can help them in planning and controlling the process, and of designers requiring them for supporting their design decisions. Hence, the thesis aims to focus on product costs to understand its influence on design decisions as well as on the overall management of the product development process. The core part of the thesis is based on the models and methods developed for enhancing cost analysis at the beginning of the product development process. This investigation aims to determine the importance of cost estimation in improving the overall performance of a newly designed product. The focus on post-sales and, more generally, on the customer, has become so relevant that manufacturers have to take into account not only the most obvious aspects about the product and related services, but even consider the associated implications for customers during product use. However, implementing a product life cycle perspective is still a challenging process for companies. From a methodological perspective, the reasons include uncertainty regarding the available approaches and ambiguity about their application. In terms of implementation, the main challenge is the long-term cost management, when one considers uncertainty in process duration, data collection, and other supply chain issues. In fact, helping designers and managers efficiently understand the strategic and operational consequences of a cost analysis implementation is still a problem, although advanced methodologies for more in-depth and timely analyses are available. And this is even more if one considers that product lifecycle represents a critical area of investment, particularly in light of the new challenges and opportunities provided by big data analysis in the Industry 4.0 contexts. This dissertation addresses these aspects and provides a methodological approach to assess a rigorous implementation of life-cycle cost while discussing the evidence derived from its operational and strategic impacts. The novelty lies in the way the data and information are collected, dynamically moving the focus of the investigation with regard to the data aggregation level and the product structure. The way the techniques have been combined represents a further aspect of novelty. In fact, the introduced approach contributes to a new trend in the Product Cost Estimation (PCE) literature, which suggests the integration of different techniques for product life-cycle cost analysis. The findings obtained at the end of the process can be employed to assess the impact of platform design strategy and variety proliferations on the total life-cycle costs. By evaluating the possible mix of options, and hence offering the optimal product configuration, a more conscious way for planning the product portfolio has been provided. In this sense, a detailed operational analysis (as the cost estimation) is used to inform and drive the strategic planning of the portfolio. Finally, the thesis discusses the future opportunities and challenges for product cost analysis, assessing how digitalisation of manufacturing operations may affect the data gathering and analysis process. In this new environment, the opportunity for a more informed, cost-driven decision-making will multiply, leading to varied opportunities in this research field

A Survey of Tabu Search in Combinatorial Optimization

Tabu search is a Meta heuristic loosely connected to evolutionary computing. It has been used to tackle hard problems, especially combinatorial optimization problems. Tabu search is designed to overcome difficult regions of a search space by imposing restrictions. Various methods for diversification and intensification are applied depending on the particular problem type and on what type of solutions (within the set of good solutions) are sought. Tabu search uses memory - short term, long term and intermediate - to achieve diversification and intensification. Furthermore, aspiration criteria may be used to tune the optimization process. Thus the Tabu search Meta heuristic is very general. Different variants of the Tabu search Meta heuristic are presented in the context of combinatorial optimization. Problems discussed include the travelling salesman problem, various graph problems, and scheduling

Aplicação de ferramentas LEAN a uma linha de produção

Mestrado em Engenharia e Gestão IndustrialCada vez mais nos dias de hoje é frequente ver as empresas adotar uma filosofia lean. Desta forma as organizações pretendem ficar mais fortes e com maior capacidade de resposta às necessidades dos consumidores. Esta filosofia consiste na criação de valor para o produto através da eliminação de desperdício. É necessário um claro conhecimento das ferramentas lean, percebendo quais as suas vantagens e desvantagens para um determinado processo. O objetivo do estágio passa por analisar um determinado setor de uma empresa, tentando que todo o processo associado decorra em fluxo, sem que haja acumulação de stock intermédio entre postos. Para isso é necessário otimizar todos os processos, eliminando todas as formas de desperdício. Depois da implementação de ferramentas lean, são analisados os resultados bem como o impacto que essas mudanças causaram no setor. É importante adotar uma postura de melhoria contínua, tendo sempre em mente que nunca nada está totalmente otimizado e que é sempre possível fazer melhor.These days it is common to see companies seeking to adopt a lean philosophy. With this organizations aim to get stronger and more responsive to consumer needs. This philosophy consists on the creation of value for the product by elimination of waste. A clear understanding of lean tools is needed, to figure out what are their advantages and disadvantages for a given process. The goal of the internship involves analyzing a particular sector of a company, trying to get all the associated process arises in flow, without accumulation of intermediate stock between posts. For this it is necessary to optimize all processes, elimination all forms of waste. After the implementation of lean tools, the results are analyzed and the impact that these changes had caused on that company sector. It is important to adopt a continuous improvement, always bearing in mind that nothing is ever fully optimized and it is always possible to do better

Statistical Analysis of Machining Processes of Composite Materials

RÉSUMÉ : Le perçage dans les matériaux composites constitue un prérequis essentiel pour faciliter leur assemblage. L'un des principaux défis en matière de perçage est de fournir une excellente finition du produit et de minimiser les coûts de production. L'objectif de ce mémoire est d'étudier la relation entre la vitesse d’avance/vitesse de rotation et les caractéristiques de qualité du processus de perçage définies par: le délaminage à l'entrée et la sortie, la rugosité de la surface, l’erreur du diamètre à l’entrée et la sortie, et la circularité à l’entrée et la sortie. En outre, trois variables mesurables, non contrôlables par l’opérateur, (force de poussée, force de découpe et moment de torsion) sont analysées afin de comprendre comment ils réagissent au changement de la vitesse d'avance et de rotation, ainsi que la façon dont ils affectent les caractéristiques de qualité. Les méthodes de régression linéaire, linéaire multiple et non linéaire sont développées pour comprendre l'effet et l'importance de chaque variable d'entrée sur les caractéristiques de qualité du processus. Ce mémoire présente la collecte de données faite durant le perçage, leur modélisation mathématique et leur analyse statistique. En plus, le rôle et l’implication de chaque caractéristique de qualité dans le processus de perçage sont documentés. La méthode de régression linéaire multiple a démontré des bons résultats dans le cas des variables suivantes: force de poussée, force de découpe, moment de torsion, délaminage à l’entrée et sorite. Cette application n’est pas recommandée pour l’analyse ainsi que la prédiction des autres variables. De plus, les résultats indiquent d’une part que la vitesse d’avance a énormément d’impact sur toutes les variables de sorties étudiées, y compris les variables mesurables, à l'exception de la circularité à l'entrée. D'autre part, l’impact de la vitesse de rotation s’est avéré significatif sur les variables suivantes: la force de poussée, le délaminage à la sortie, l’erreur de diamètre à l'entrée et la sortie et la circularité à la sortie. Ainsi, dans le but de combiner les variables d’entrées avec les variables mesurables, l'application de l'analyse de covariance est développée, mais les résultats se sont avérés non concluants en raison de la forte corrélation présente entre les variables d'entrée. Par conséquent, la méthode de covariance est incohérente et non valable dans le processus du perçage. En conclusion, les résultats établissent un modèle de prédiction mathématique qui explique et surtout quantifier l'influence des variables d’entrée sur les caractéristiques de qualité du processus de perçage. Cette étude démontre également comment ces variables sont reliées et corrélées entre eux.----------ABSTRACT : Hole drilling in composite materials is an essential requirement in facilitating their assembly. One of the main challenges in drilling is providing an excellent product finish and achieving cost effectiveness. The purpose of this dissertation is to investigate the relationship between the feed rate/spindle speed and the drilling quality characteristics as defined by: delamination at entry, delamination at exit, surface roughness, diameter at entry, diameter at exit, circularity at entry and circularity at exit. Also, three measurable variables (thrust force, cutting force and torque) are analyzed to understand how they relate to the feed rate and the spindle speed as well as how they affect the other quality characteristics. Multiple linear and nonlinear regression techniques are used to understand the effect and the importance of each input variable on the quality outputs. Data collection, mathematical modeling and statistical analysis were utilized in this dissertation. Furthermore, the role of each quality characteristics in drilling process is documented as well as the measurable variables. Results show that the multiple regression models showed significance in a subset of the outputs (thrust force, cutting force, torque, delamination at entry and delamination at exit) and proved insignificant on the study of the other drilling quality characteristics. The results also indicate that of all the variables studied including the measurable variables, the feed rate appeared to be the most significant on the outputs except for the circularity at entry. On the other hand, the spindle speed was shown to impact significantly the following variables: trust force, delamination at exit, diameter error at exit and entry, and circularity at exit. Furthermore, the application ANCOVA methodology is investigated on the drilling outputs but it provided inconclusive results due to strong correlation among the input variables. Therefore, the ANCOVA methodology was deemed not suitable in the study of this drilling process. In conclusion, the results establish a mathematical prediction model that explains and more importantly quantifies the influence of the various variables (inputs) on the quality characteristics of the drilling process (outputs). This novel model also demonstrates how these variables are related amongst each other