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Blank M.,University of Oldenburg | Lehnhoff S.,Institute for Information Technology
IEEE International Conference on Industrial Informatics (INDIN) | Year: 2013

The energy system is due to substantial changes by reason of an ongoing decentralization of power supply. A challenge will be to provide ancillary services by distributed units since they are volatile regarding their power feed-in and hard to predict. This paper presents a method that allows for the evaluation of how reliable distributed units can participate in the provision of ancillary service products. This method can be used in order to assess unit coalitions with respect to their reliability. © 2013 IEEE. Source

Niesse A.,Institute for Information Technology | Sonnenschein M.,University of Oldenburg
SMARTGREENS 2013 - Proceedings of the 2nd International Conference on Smart Grids and Green IT Systems | Year: 2013

Transforming the electric power system to incorporating a considerably increased share of renewable distributed generation implicates new challenges for the control of the system. To overcome the known shortcomings of centralized control, e.g. regarding scalability and robustness, a decentralized, self-organized system of agents for generators, loads and storages is widely discussed. We focus on a dynamic aggregation of these units to participate on current and future energy markets for both active power and new ancillary services products. With these units participating in system services, rescheduling of units within clusters becomes a more complex task that should reflect grid usage properties. In this work, we develop grid related cluster schedule resemblance as a metric to analyze the grid usage changes using graph theory. This metric can be used to compare different rescheduling options regarding grid usage for both dynamic clusters of distributed energy resources and for rescheduling of static clusters like virtual power plants. An example is used to show that this metric can be used as a separate optimization target for the multi-criteria optimization problem of cluster rescheduling. Source

Kneib T.,University of Gottingen | Winter A.,Carl von Ossietzky University | Rohde M.,Institute for Information Technology | Henke R.-P.,Institute of Pathology Oldenburg | Wawroschek F.,Carl von Ossietzky University
Urologia Internationalis | Year: 2015

Existing nomograms predicting lymph node involvement (LNI) in prostate cancer (PCa) are based on conventional lymphadenectomy. The aim of the study was to develop the first nomogram for predicting LNI in PCa patients undergoing sentinel guided pelvic lymph node dissection (sPLND). Materials and Methods: Analysis was performed on 1,296 patients with PCa who underwent radioisotope guided sPLND and retropubic radical prostatectomy (2005.2010). Median prostate specific antigen (PSA): 7.4 ng/ml (IQR ng/ml). Clinical T-categories: T1: 54.8%, T2: 42.4%, T3: 2.8%. Biopsy Gleason sums: ≤ 6: 55.1%, 7: 39.5%, ≥ 8: 5.4%. Multivariate logistic regression models tested the association between all of the above predictors and LNI. Regression-based coefficients were used to develop a nomogram for predicting LNI. Accuracy was quantified using the area under the curve (AUC). Results: The median number of LNs removed was 10 (IQR 7.13). Overall, 17.8% of patients (n = 231) had LNI. The nomogram had a high predictive accuracy (AUC of 82%). All the variables were statistically significant multivariate predictors of LNI (p = 0.001). Univariate predictive accuracy for PSA, Gleason sum and clinical stage was 69, 75 and 69%, respectively. Conclusions: The sentinel nomogram can predict LNI at a sPLND very accurately and, for the first time, aid clinicians and patients in making important decisions on the indication of a sPLND. The high rate of LN+ patients underscores the sensitivity of sPLND. © 2015 S. Karger AG, Basel. Source

Onken M.,Institute for Information Technology
Studies in Health Technology and Informatics | Year: 2012

Over the last years there has been a strong trend of publishing health data in anonymized format in order to make it available for research. This is also true for medical imaging where the DICOM standard is the predominant data format and network protocol. This paper proposes an extension to any DICOM networking infrastructure that permits sharing of medical images in an anonymized way. Standard DICOM software is utilized on client and server side. While offering researchers access to all images in anonymous format, the architecture enables authorized clinicians to access the same images including their original patient information (name, institution, etc.). Identifying parts and anonymous parts of the image data are stored to geologically different databases. Together with sophisticated network protocols, patient privacy is fully preserved. © 2012 European Federation for Medical Informatics and IOS Press. All rights reserved. Source

Ellen C.,Institute for Information Technology | Sieverding S.,Institute for Information Technology | Hungar H.,German Aerospace Center
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2014

The formal specification of functional requirements can often lead to inconsistency as well as unintended specification, especially in the early stages within the development process. In this paper, we present a formal model checking approach which tackles both of these problems and is also applicable during the requirements elicitation phase, in which no component model is available. The presented notion of consistency ensures the existence of at least one possible run of the system, which satisfies all requirements. To avoid trivial execution traces, the "intended" functional behavior of the requirements is triggered. The analysis is performed using model checking. More specifically, to reduce the overall analysis effort, we apply a bounded model checking scheme. If the set of requirements is inconsistent the method also identifies a maximal sub-set of consistent requirements. Alternatively, a minimal inconsistent sub-set can be computed. The approach is demonstrated on a railway crossing example using the BTC Embedded Specifier and the iSAT model checker. © 2014 Springer International Publishing. Source

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