540 research outputs found

    Efficient interface conditions for the finite difference beam propagation method

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    It is shown that by adapting the refractive indexes in the vicinity of interfaces, the 2-D beam propagation method based on the finite-difference (FDBPM) scheme can be made much more effective. This holds especially for TM modes propagating in structures with high-index contrasts, such as surface polaritons. A short discussion is given on the applicability of the FDBP

    An experience in modelling business process architecture

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    We present a mapping of a previously designed Business Process Architecture (BPA) meta-model onto ArchiMate, i.e., the de facto standard Enterprise Architecture (EA) modelling language. This construct mapping allows developing process maps, i.e., descriptions of (views of) the business process architecture of an organization. We demonstrate the development of these process maps using the Signavio Business Process Management (BPM) modelling platform. The developed process maps are part of the organization’s enterprise architecture model and are linked to BPMN process diagrams that detail the functional, control-flow, data and resource aspects of the business processes included in the process map. Our research contributes to the integration of BPM and EA by researching BPA as a concept common to both disciplines

    Intermittent chaotic chimeras for coupled rotators

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    Two symmetrically coupled populations of N oscillators with inertia mm display chaotic solutions with broken symmetry similar to experimental observations with mechanical pendula. In particular, we report the first evidence of intermittent chaotic chimeras, where one population is synchronized and the other jumps erratically between laminar and turbulent phases. These states have finite life-times diverging as a power-law with N and m. Lyapunov analyses reveal chaotic properties in quantitative agreement with theoretical predictions for globally coupled dissipative systems.Comment: 6 pages, 5 figures SUbmitted to Physical Review E, as Rapid Communicatio

    Special Issue Editorial – Accumulation and Evolution of Design Knowledge in Design Science Research: A Journey Through Time and Space

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    Sir Isaac Newton (1676) famously said, “If I have seen further, it is by standing on the shoulders of giants.” Research is a collaborative, evolutionary endeavor—and it is no different with design science research (DSR), which builds upon existing design knowledge and creates new design knowledge to pass on to future projects. However, despite the vast, growing body of DSR contributions, scant evidence of the accumulation and evolution of design knowledge has been articulated in an organized DSR body of knowledge. Most contributions rather stand on their own feet than on the shoulders of giants, and this continues to limit how far we can see, curtailing the extent of the broader impacts that can be made through DSR. In this editorial, we aim at providing guidance on how to position design knowledge contributions in wider problem and solution spaces. We propose (1) a model conceptualizing design knowledge as a resilient relationship between problem and solution spaces, (2) a model that demonstrates how individual DSR projects consume and produce design knowledge, (3) a map to position a design knowledge contribution in problem and solution spaces, and (4) principles on how to use this map in a DSR project. We show how fellow researchers, readers, editors, and reviewers, as well as the IS community as a whole, can make use of these proposals, and also illustrate future research opportunities

    Towards A Method for Developing Reference Enterprise Architectures

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    In most economic sectors organizations face rapid environmental changes like regulations. Such changes can force them to adjust both their organizational and operational structure. For instance, in the energy utility sector numerous developments moved German Public Utilities (PUs) towards a liberalized market. Nowadays PUs have to stay competitive while managing a heterogeneous information technology (IT) landscape. We address this demand for aligning business and IT by combining the holistic perspective of Enterprise Architecture Management (EAM) with the characteristic of reference modeling to reuse knowledge in a problem domain. Therefore, we utilize configurative reference modeling within Design Science Research (DSR). The artefact at hand is a method for developing a Reference Enterprise Architecture (R-EA), which is applied in the problem domain of PUs. Our contributions are the (i) adaptation of Configurative Reference Modelling (CRM) to develop a R-EA and (ii) a procedure how to elicit knowledge for R-EA development method

    Remote Navigation and Contact-Force Control of Radiofrequency Ablation Catheters

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    Atrial fibrillation (AF), the most common and clinically significant heart rhythm disorder, is characterized by rapid and irregular electrical activity in the upper chambers resulting in abnormal contractions. Radiofrequency (RF) cardiac catheter ablation is a minimally invasive curative treatment that aims to electrically correct signal pathways inside the atria to restore normal sinus rhythm. Successful catheter ablation requires the complete and permanent elimination of arrhythmogenic signals by delivering transmural RF ablation lesions contiguously near and around key cardiac structures. These procedures are complex and technically challenging and, even when performed by the most skilled physician, nearly half of patients undergo repeat procedures due to incomplete elimination of the arrhythmogenic pathways. This thesis aims to incorporate innovative design to improve catheter stability and maneuverability through the development of robotic platforms that enable precise placement of reproducibly durable ablation lesions. The first part of this thesis deals with the challenges to lesion delivery imposed by cardiorespiratory motion. One of the main determinants of the delivery of durable and transmural RF lesions is the ability to define and maintain a constant contact force between the catheter tip electrode and cardiac tissue, which is hampered by the presence of cardiorespiratory motion. To address this need, I developed and evaluated a novel catheter contact-force control device. The compact electromechanical add-on tool monitors catheter-tissue contact force in real-time and simultaneously adjusts the position of a force-sensing ablation catheter within a steerable sheath to compensate for the change in contact force. In a series of in vitro and in vivo experiments, the contact-force control device demonstrated an ability to: a) maintain an average force to within 1 gram of a set level; b) reduce contact-force variation to below 5 grams (2-8-fold improvement over manual catheter intervention); c) ensure the catheter tip never lost contact with the tissue and never approached dangerous force levels; and importantly, d) deliver reproducible RF ablation lesions regardless of cardiac tissue motion, which were of the same depth and volume as lesions delivered in the absence of tissue motion. In the second part of the thesis, I describe a novel steerable sheath and catheter robotic navigation system, which incorporates the catheter contact-force controller. The robotic platform enables precise and accurate manipulation of a remote conventional steerable sheath and permits catheter-tissue contact-force control. The robotic navigation system was evaluated in vitro using a phantom that combines stationary and moving targets within an in vitro model representing a beating heart. An electrophysiologist used the robotic system to remotely navigate the sheath and catheter tip to select targets and compared the accuracy of reaching these targets performing the same tasks manually. Robotic intervention resulted in significantly higher accuracy and significantly improved the contact-force profile between the catheter tip and moving tissue-mimicking material. Our studies demonstrate that using available contact-force information within a robotic system can ensure precise and accurate placement of reliably transmural RF ablation lesions. These robotic systems can be valuable tools used to optimize RF lesion delivery techniques and ultimately improve clinical outcomes for AF ablation therapy

    Application Portfolio Management—An Integrated Framework and a Software Tool Evaluation Approach

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    Despite the growing number of organizations that have lost track of their application landscape and have suffered from a sharp increase in application portfolio complexity, a comprehensive and systematic approach to Application Portfolio Management (APM) still appears far from being adopted. To move the adoption process along, this paper develops a comprehensive framework assimilating and extending previous research and presents an APM process comprising data collection, analysis, decision-making, and optimization phases. This paper also presents an approach for evaluating software tools for APM and identifies which software tool families are best able to provide support for specific purposes. With this integrated conceptual guideline for APM and its translation into a model for measuring appropriate practical support, this paper not only allows for a move more deeply into the research area but also offers advice for both researchers and practitioners

    Method support for enterprise architecture management capabilities

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    "What can our EA organization do and/or what should it be capable of?". In order to answer this questions, a capability-based method is developed, which assists in the identification, structuring and management of capabilities. The approach is embedded in a process comprising four building blocks providing appropriated procedures, concepts and supporting tools evolved from theory and practical use cases. The guide represents a flexible method for capability newcomers and experienced audiences to optimize enterprises’ economic impacts of EAM supporting the alignment of business and IT.„Was muss unser UAM leisten können?“ Als Grundlage für die Beantwortung dieser Frage sollen Konzepte aus dem Fähigkeitenmanagement genutzt werden. Im Rahmen dieser Arbeit wird eine fähigkeitenbasierte Methode entwickelt, welche Unternehmen bei der Identifikation, Strukturierung und Verwaltung von UAM-Fähigkeiten unterstützt. Der Ansatz ist in einen Prozess eingegliedert, welcher vier Hauptbestandteile beinhaltet und die für die Durchführung notwendigen Vorgehen, Konzepte und Hilfsmittel beschreibt, welche wiederrum in Kooperationen mit der Praxis getestet wurden
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