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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Demand Responsive Planning : A dynamic and responsive planning framework based on workload control theory for cyber-physical production systems

Akillioglu, Hakan January 2015 (has links)
Recent developments in the area of Cyber-Physical Production Systems prove that high technology readiness level is already achieved and industrialization of such technologies is not far from today. Although these technologies seem to be convenient in providing solutions to environmental uncertainties, their application provides adaptability only at shop floor level. Needless to say, an enterprise cannot reach true adaptability without ensuring adaptation skills at every level in its hierarchy. Commonly used production planning and control approaches in industry today inherit from planning solutions which are developed in response to historical market characteristics. However, market tendency in recent years is towards making personalized products a norm. The emerging complexity out of this trend obliges planning systems to a transition from non-recurring, static planning into continuous re-planning and re-configuration of systems. Therefore, there is a need of responsive planning solutions which are integrated to highly adaptable production system characteristics. In this dissertation, Demand Responsive Planning, DRP, is presented which is a planning framework aiming to respond to planning needs of shifting trends in both production system technologies and market conditions. The DRP is based on three main constructs such as dynamicity, responsiveness and use of precise data. These features set up the foundation of accomplishing a high degree of adaptability in planning activities. By this means, problems from an extensive scope can be handled with a responsive behavior (i.e. frequent re-planning) by the use of precise data. The use of precise data implies to execute planning activities subject to actual demand information and real-time shop floor data. Within the context of the DRP, both a continuous workload control method and a dynamic capacity adjustment approach are developed. A test-bed is coded in order to simulate proposed method based on a system emulation reflecting the characteristics of cyber-physical production systems at shop floor level. Continuous Precise Workload Control, CPWLC, method is a novel approach aiming at precise control of workload levels with the use of direct load graphs. Supported by a multi-agent platform, it generates dynamic non-periodic release decisions exploiting real time shop floor information. As a result, improved shop floor performances are achieved through controlling workload levels precisely by the release of appropriate job types at the right time. Presented dynamic capacity adjustment approach utilizes rapid re-configuration capability of cyber-physical systems in achieving more frequent capacity adjustments. Its implementation architecture is integrated to the CPWLC structure. By this means, a holistic approach is realized whereby improved due date performance is accomplished with minimized shop floor congestion. Hence, sensitivity to changing demand patterns and urgent job completions is improved. / <p>QC 20150907</p>
2

Characterisation of the Business Models for Innovative, Non-Mature Production Automation Technology

Maffei, Antonio January 2012 (has links)
Manufacturing companies are nowadays facing an unprecedented series of challenges to their survival: global competition and product mass-customization are the shaping forces of tomorrow’s business success. The consequent need for agile and sustainable production solutions is the utmost motivation behind the development of innovative approaches which often are not in line with the state of art. It is well documented that companies fail in recognizing how such disruptively innovative approaches can yield an interesting economic output. This, in turn, enhances the risk of leaving the aforementioned promising technologies conceptually and practically underdeveloped.  In the field of automatic production systems the Evolvable Production System paradigm proposes modular architectures with distributed, autonomous control rather than integral design and hierarchical, centralized control. EPS technology is thus disruptive: it refuses the present paradigm of Engineer to Order in industrial automation by proposing an advanced Configure to Order system development logic. This dissertation investigates the possibility of using the recent sophisticated developments of the concept of Business Model as a holistic analytical tool for the characterization and solution of the issue of bringing disruptive and non-fully mature innovation to proficient application in production environments. In order to purse this objective the main contributions in the relevant literature have been extracted and combined to an original definition of business model able to encompass the aspects deemed critical for the problem. Such a construct is composed of three elements: (1) Value Proposition that describe the features of a technology that generates value for a given customer, (2) the Value Configuration and the (3) Architecture of the Revenue which describe the mechanisms that allows to create and capture such value respectively.    The subsequent work has focused on the EPS paradigm as a specific case of the overall problem. The first step has been a full characterization of the related value proposition through an innovative approach based on a bottom-up decomposition in its elementary components, followed by their aggregation into meaningful value offerings: with reference to the EPS paradigm such an approach has disclosed an overall value proposition composed of six potentially independent value offerings. This collection of Value Offerings has then been used as a basis to generate the EPS business models. In particular for each single offering a possible set of necessary activities and resources has been devised and organized in a coherent value configuration. The resulting creation mechanisms have then been linked among each other following a logical supplier-customer scheme for capturing the value: this allowed establishing the architecture of revenue, last element of the overall production paradigm. Finally the results have been validated in a semi-industrial system developed for the (IDEAS, 2010-2013) project through the individuation of the areas of application of such business models. / <p>QC 20121120</p> / FP7-IDEAS- Instantly Deployable Evolvable Assembly System / FP6- EUPASS-Evolvable Ultra-Precision Assembly Systems / XPRES- Initiative for excellence in production research
3

Towards a Holistic Development Approach for Adaptable Manufacturing Paradigms : A Case Study of Evolvable Production Systems

Rahatulain, Afifa January 2016 (has links)
Increasing global competition, market uncertainties and high product variance are a few of the factors posing challenges to the existing manufacturing industry. Having a quick response to market fluctuations and adapting to changing customer demands while maintaining shorter lead times and low costs are a few of the major challenges. The main focus of this thesis is on Evolvable Production Systems, which is one of the promising solutions to deal with the emerging manufacturing challenges by changing the conventional manufacturing systems towards a more flexible, intelligent and adaptable approach. Although promising, further research is needed in several directions for a wider industrial acceptance of EPS. The directions include but are not limited to methodological aspects, tool support, etc. throughout the development lifecycle. This thesis aims to provide a basis for a holistic model-based development methodology for evolvable production systems. One of the main contributionsof this work is the identification of major architectural elements (i.e stakeholders,concerns, viewpoints and views) and their dependencies on each other.This work shall serve as a basis for establishing a well-defined architectural framework for EPS. The second important contribution of this thesis is the development of a domain specific modeling language (EPS- DSL) based on the existing EPS ontology. The DSM platform does not only store the domain knowledge in the form of models but also provides support for the re-use of these models, i.e. enables utilization of the domain ontology during system development. Moreover, the automatic code generation support for the module library presented in this work, significantly reduces the risks of information discrepancies when transferring data from one abstraction level to another. The existing EPS ontology is also evaluated from a holistic perspective and resulted in contributing a few improvement suggestions for achieving a seamless model-based development approach. Evaluation of Simulink/SimEvents as a modeling and simulation tool for EPS is the third main contribution of this thesis. One of the main advantages of evaluating this tool for EPS is the opportunity to analyze the complete system behavior on a single modeling platform. The integration of agent-based system behavior (discrete event) with dynamic system behavior (continuous &amp; discrete time) provides a holistic modeling approach and implies less information inconsistencies. / <p>QC 20160429</p>
4

System Evaluation and Learning in Evolvable Production Systems : Preliminary considerations and research directions

Neves, Pedro January 2012 (has links)
Dynamicity and unpredictability related to markets is strongly hardening companies’ mission to follow them and satisfy customer needs mainly due to the lack of adequate engineering mechanisms. These effects are felt more intensively in markets where low volumes and high customisation are needed since this requires constant changes in systems that can range from simple setups to total line re-configuration and re-programing. State of the Art Industrial technology has historically been driven to achieve very efficient and flexible production lines for pre-thought problems; however this technology doesn’t satisfy the needs faced by current production requirements where adaptability and responsiveness are off the essence. The last decade witnessed the advent of Evolvable Production Systems (EPS) and other modern paradigms that offer promising approaches to substitute obsolete production strategies. EPS enhances system re-configurability using process-oriented modularity and multi-agent based distributed control endowing the system with units that are autonomous, self-organizing and functionality-oriented. The aggregation of these independent units will then form a system that with a well-defined system architecture and interactions rules can collaborate to complete production plans and react to unpredictable events without re-programing needs. The complexity associated with combinatorial possibilities of forming a system based in such premises raises the need to study how such system performance can be evaluated and how machine learning can be used to discover best system configurations for specific cases. This thesis goal is to enlighten the relation between EPS characteristics, Evaluation and Learning building the foundations for the achievement of Evaluation and Learning mechanisms that can contribute to better system design and configuration to improve system performance and autonomy, and contribute to a more economical solution. / <p>QC 20121218</p>

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