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Search Results: 1 - 10 of 9921 matches for " Frank Leymann "
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An Evidence Model to Enable Constraint-Based Runtime Monitoring in SOA
Ganna Monakova,Philip Miseldine,Frank Leymann
Lecture Notes in Engineering and Computer Science , 2010,
Pattern-Based Development and Management of Cloud Applications
Christoph Fehling,Frank Leymann,Jochen Rütschlin,David Schumm
Future Internet , 2012, DOI: 10.3390/fi4010110
Abstract: Cloud-based applications require a high degree of automation regarding their IT resource management, for example, to handle scalability or resource failures. This automation is enabled by cloud providers offering management interfaces accessed by applications without human interaction. The properties of clouds, especially pay-per-use billing and low availability of individual resources, demand such a timely system management. We call the automated steps to perform one of these management tasks a “management flow”. Because the emerging behavior of the overall system is comprised of many such management flows and is often hard to predict, we propose defining abstract management flows, describing common steps handling the management tasks. These abstract management flows may then be refined for each individual use case. We cover abstract management flows describing how to make an application elastic, resilient regarding IT resource failure, and how to move application components between different runtime environments. The requirements of these management flows for handled applications are expressed using architectural patterns that have to be implemented by the applications. These dependencies result in abstract management flows being interrelated with architectural patterns in a uniform pattern catalog. We propose a method by use of a catalog to guide application managers during the refinement of abstract management flows at the design stage of an application. Following this method, runtime-specific management functionality and management interfaces are used to obtain automated management flows for a developed application.
Process Fragment Libraries for Easier and Faster Development of Process-based Applications
David Schumm,Dimka Karastoyanova,Oliver Kopp,Frank Leymann
Journal of Systems Integration , 2011,
Abstract: The term “process fragment” is recently gaining momentum in business process management research. We understand a process fragment as a connected and reusable process structure, which has relaxed completeness and consistency criteria compared to executable processes. We claim that process fragments allow for an easier and faster development of process-based applications. As evidence to this claim we present a process fragment concept and show a sample collection of concrete, real-world process fragments. We present advanced application scenarios for using such fragments in development of process-based applications. Process fragments are typically managed in a repository, forming a process fragment library. On top of a process fragment library from previous work, we discuss the potential impact of using process fragment libraries in cross-enterprise collaboration and application integration.
A Classification of BPEL Extensions
Oliver Kopp,Katharina G?rlach,Dimka Karastoyanova,Frank Leymann
Journal of Systems Integration , 2011,
Abstract: The Business Process Execution Language (BPEL) has emerged as de-facto standard for business processes implementation. This language is designed to be extensible for including additional valuable features in a standardized manner. There are a number of BPEL extensions available. They are, however, neither classified nor evaluated with respect to their compliance to the BPEL standard. This article fills this gap by providing a framework for classifying BPEL extensions, a classification of existing extensions, and a guideline for designing BPEL extensions.
Solution for Rational Expectation Models Free of Complex Numbers  [PDF]
Frank Hespeler
Theoretical Economics Letters (TEL) , 2011, DOI: 10.4236/tel.2011.13011
Abstract: This paper approaches the problem of the potential for complex-valued solutions within linear macroeconomic models with rational expectations. It finds that these problems are associated with a specific solution method for the underlying model. The paper establishes that the danger of complex-valued solutions always can be eliminated by forcing those solutions to fulfill additional constraints. These constraints are essentially restrictions on the degrees of freedoms in indeterminate solutions.
A Characterization of the Optimal Management of Heterogeneous Environmental Assets under Uncertainty  [PDF]
Frank Raymond
Theoretical Economics Letters (TEL) , 2012, DOI: 10.4236/tel.2012.25093
Abstract: The application herein involves the optimal management of renewable and nonrenewable resources within the context of a stochastic model of optimal control. By characterizing the two dimensional Bellman solution, three rules with respect to resource management are established. Within the context of coastal development, this analysis may help to explain why renewable resources may become increasingly vulnerable to random external shocks as nonrenewable resources are depleted. Although existence of an optimal closed form solution to the multi-sector Bellman model remains an open mathematical question, this analysis offers a characterization which can be applied to other scenarios in economics or finance in which two assets following stochastic processes interact.
Intensity fluctuations in bimodal micropillar lasers enhanced by quantum-dot gain competition
H. A. M. Leymann,C. Hopfmann,F. Albert,A. Foerster,M. Khanbekyan,C. Schneider,S. H?fling,A. Forchel,M. Kamp,J. Wiersig,S. Reitzenstein
Physics , 2013, DOI: 10.1103/PhysRevA.87.053819
Abstract: We investigate correlations between orthogonally polarized cavity modes of a bimodal micropillar laser with a single layer of self-assembled quantum dots in the active region. While one emission mode of the microlaser demonstrates a characteristic s-shaped input-output curve, the output intensity of the second mode saturates and even decreases with increasing injection current above threshold. Measuring the photon auto-correlation function g^{(2)}(\tau) of the light emission confirms the onset of lasing in the first mode with g^{(2)}(0) approaching unity above threshold. In contrast, strong photon bunching associated with super-thermal values of g^{(2)}(0) is detected for the other mode for currents above threshold. This behavior is attributed to gain competition of the two modes induced by the common gain material, which is confirmed by photon crosscorrelation measurements revealing a clear anti-correlation between emission events of the two modes. The experimental studies are in excellent qualitative agreement with theoretical studies based on a microscopic semiconductor theory, which we extend to the case of two modes interacting with the common gain medium. Moreover, we treat the problem by an extended birth-death model for two interacting modes, which reveals, that the photon probability distribution of each mode has a double peak structure, indicating switching behavior of the modes for the pump rates around threshold.
Investigating the Suitability of Agile Methods for Requirements Development of Home Care Systems  [PDF]
Sandra Kelly, Frank Keenan
Journal of Software Engineering and Applications (JSEA) , 2010, DOI: 10.4236/jsea.2010.39104
Abstract: The ageing population in developed countries brings many benefits but also many challenges, particularly in terms of the development of appropriate technology to support their ability to remain in their own home environment. One particular challenge reported for such Home Care Systems (HCS) is the identification of an appropriate requirements development technique for dealing with the typical diverse stakeholders involved. Agile Methods (AMs) recognize this challenge and propose techniques that could be useful. This paper examines the desirable characteristics identified for requirements development in HCS and investigates the extent to which agile practices conform to these. It also sets out future work to improve the situation for the non compliant points found.
Free Anterolateral Thigh Perforator Flap for Head and Neck Cancer Resection in a Nonagenarian  [PDF]
Frank Lin, Damien Grinsell
Modern Plastic Surgery (MPS) , 2012, DOI: 10.4236/mps.2012.21001
Abstract: With an aging population, free flap reconstruction for head and neck cancer ablation in the elderly is becoming more commonplace. In nonagenarians, however, such major operations are still rarely offered due to its physiological demands. We report the first case of successful resection and reconstruction of head and neck cancer with a free perforator flap in a 96 year old patient. We feel that with careful patient and flap selection, careful preoperative workup and close collaboration between treating teams, age alone should not preclude patients from receiving the best possible curative treatment and reconstruction in head and neck cancers. Even in nonagenarians, perforator free flaps, such as the anterolateral thigh flap, can be used safely to achieve good functional and aesthetic outcomes.
Optical Modeling and Analysis of Peripheral Optics of Contact Lenses  [PDF]
Jie Shen, Frank Spors
Open Journal of Ophthalmology (OJOph) , 2012, DOI: 10.4236/ojoph.2012.23012
Abstract: Background: Degraded peripheral vision has been hypothesized to be a stimulus for the development of foveal refractive error. Contact lenses have been widely used to correct central vision, but their impacts on peripheral vision are still unknown. The purpose of this study was to use optical model software to evaluate the peripheral optics of rigid gas permeable (RGP) and soft contact lenses (SCLs) in isolation. This will better assist us in understanding their peripheral optical performances on human eyes. Methods: An optical design software package (Zemax EE) was used to model peripheral optics of Menicon RGP lens and Acuvue 2 SCLs. Profiles of sphero-cylindrical power and major higher-order aberrations were computed in 10osteps out to 40o off-axis eccentricity for –3.0 D central focal power contact lens. The results of optical modeling were analyzed and compared with previously published experimental data. Results: –3.0 D RGP lenses and SCLs had –1.4 D and –2.0 D dioptric power at 40o eccentricity, respectively. The reduced dioptric power in the periphery of the analyzed contact lenses quantitatively matched with the reduced amount of hyperopic field curvature found from experimental data when these contact lenses fitted on human eyes. Cylindrical power increased to 0.3 D ~ 0.4 D at 40o eccentricity for both lens types. In addition, both contact lens types produced higher order aberrations, namely 1.2 μm coma and 0.15 μm spherical aberration at 40o eccentricity. Conclusions: Compared to SCLs, RGP lenses with equal focal power had less dioptric power in the periphery. Both RGP lenses and SCLs produced the same amount of major higher-order aberrations with increasing of the field angle. Some of these results can be used to predict and understand the peripheral optical performance of contact lenses on human eyes.
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