Traditional approaches to solve non-Markovian models use phase-type expansions, apply the method of supplementary variables or construct an embedded Markov chain. All three approaches have also been investigated in the context of queuing networks and stochastic Petri nets. The phase-type expansion approach suffers from the enlargement of the state space, whereas the method of supplementary variables and the embedded Markov chain construction require basically that non-exponentially timed activities are not concurrent. If they are concurrent this will result in multidimensional differential equations that are hard to solve.
To avoid these problems more efficient techniques for the performance evaluation of computer networks like web servers or networks of embedded systems have to be developed. In such systems activity durations with large variances (file transfers) as well as deterministic durations (security aspects) arise. We have created two new approaches to approximately evaluate the performance models of these systems; the first one is based on the method of supplementary variables and the second one deals with phase-type expansions. We are currently enhancing these approaches and it is planned to combine them for the solution of large non-Markovian models.
In cooperation with department 4 (Distributed Systems and Operating Systems) the tool WinPEPSY for performance evaluation and prediction of queueing systems was developed. It contains well known analysis methods for open and closed product form and non-product form networks (mean value analysis, Jackson-method, decomposition methods, simulation) and the new state-based analysis methods are integrated.
In a cooperation with the Telecommunications Laboratory, Communications, Electronics and Information Engineering Division of the National Technical University of Athens simulation models for embedded network processors have been developed. The goal is to enhance the above mentioned methods, so that even performance measures for these large models can be derived.
- Keywords: Non-Markovian models; stochastic petri nets; queueing networks; performance analysis; approximation algorithms
- Project Period: 2001-11-01 - 2004-10-30
- "WinPEPSY-QNS-Performance Evaluation and Prediction System for Queueing Networks," Proc.13th GI/ITG Conference, Berlin, Nürnberg, Germany, pp. 465-468, March 2006 ,
- "Approximate Analysis of Stochastic Models by Self-Correcting Aggregation," Proc. 2nd. Int. Conf. on the Quantitative Evaluation of Systems 2005, Torino, Italy, pp. 134-143, September 2005 ,
- "An iterative approximate analysis method for non-Markovian models based on supplementary variables," Proc. 12th GI/ITG Conf. on Measuring, Modelling and Evaluation of Computer and Communication Systems, Dresden, pp. 255-264, September 2004 ,
- "WinPEPSY-QNS Performance Evaluation and Prediction System for Queueing Networks," Proc. 11th Int. Conf. on Analytical and Stochastical Modelling Techniques and Applications, Magdeburg, pp. 110 -115, June 2004 ,
- "Iterative Analysis of Markov Regenerative Models," in Journal of Performance Evaluation (44), pp. 51-72, 2001 ,
- "Petri Net Modeling and Performability Evaluation with TimeNET 3.0," Proc. Int. Conf. on Modelling Techniques and Tools for Computer Performance Evaluation., Heidelberg, Schaumburg, Illinois, USA, pp. 188-202, March 2000 ,
- "Cascaded Deterministic and Stochastic Petri Nets," Proc. 3. Int. Meeting on the Numerical Solution of Markov Chains, Zaragoza, pp. 111-130, September 1999 ,
Connected Mobility @ ZOLLHOF
Im Rahmen der Lehrveranstaltung Vernetzte Mobilität und autonomes Fahren haben die Studenten am 24.01.2019 an einem Workshop am Zollhof in Nürnberg teilgenommen. Nach einer regulären Vorlesung in den Räumlichkeiten mit Gründeratmosphäre konnten die Studenten in vier Gruppen eigene Ideen im Bereich der vernetzten Mobilität ausarbeiten. Dabei waren nicht nur technische Möglichkeiten relevant, sondern auch unternehmerische und interdisziplinäre Aspekte. In drei Themenbereichen (sicherheitskritische Anwendungen, Infotainment und routenbasierte Dienste) haben die Teilnehmer mit sehr viel Motivation interessante Ideen entwickeln können und lernten das Vorgehen nach dem Lean Canvas kennen. Ein aktuelles Startup aus dem Mobilitätsbereich (Thema: kostengünstige Parksensoren) hat die eigene Geschichte erzählt und aufgezeigt wie man aus dem studentischen Umfeld erfolgreich eine Idee zum Produkt entwickeln kann. Alle Teilnehmer hatten sehr viel Spass und haben angeregt für zukünftige Teilnehmer der Lehrveranstaltung das Format zu wiederholen.
Published on 2019-02-18 14:46:56 (Permalink)
Three contributions at the WSC 2018
At the recent Winter Simulation Conference 2018 in Gothenburg (Schweden) CS7 published three contributions. Dr. Anatoli Djanatliev was a part of the track-coordination and program committee and presented a panel paper focusing on hybrid simulation. Dr. Peter Bazan published a paper about a mobility system model, and Dr. David Steber was talking about energy simulation and optimization. The Winter Simulation Conference is one of the largest forum for simulation and modeling. Since about 50 years this event brings researchers and industrial players together. The most important supporters are: ACM/SIGSIM, IISE (Institute of Industrial and Systems Engineers), INFORMS-SIM and SCS (Society for Modeling and Simulation International), ASIM (Arbeitsgemeinschaft Simulation), IEEE.
Published on 2019-01-07 10:28:58 (Permalink)
Siemens Master Prizes for our Research Assistants
Our research assistants and PhD students Anna Arestova, Wojciech Baron and Alexander Brummer (already in July 2018) have received the Siemens Master Prize as part of the graduation ceremony of the Faculty of Engineering. The prize is awarded to excellent Bachelor and Master graduates in the degree program of information and communication technology (ICT).
Published on 2018-12-20 16:06:36 (Permalink)
Paper Presentation at IEEE VNC 2018
Alexander Brummer presented the results of his paper "Measurement-Based Evaluation of Environmental Diffraction Modeling for 3D Vehicle-to-X Simulation" at this year's IEEE Vehicular Networking Conference (VNC) in Taipei, Taiwan. The conference (this time in its 10th edition) is one of the main scientific events in the field of V2X communications.
Published on 2018-12-20 15:58:30 (Permalink)
Simulation-based evaluation of Quality of Service for 5G network mobility
The networking of vehicles with other road users or the infrastructure (Vehicle-to-Everything (V2X)) is one of the key technologies for autonomous driving and smart cities. The next generation of mobile communications (5G), which is going to be launched in 2020, takes into account use cases and criteria for V2X communication from the very beginning and is a key technology for autonomous driving. Foreseen autonomous driving functions need to be able to execute safety-critical applications and infotainment applications simultaneously. In the context of competition for network resources, a 5G network needs to consider these specific Quality of Service requirements and prefer safety applications at any time. The virtualization of mobile radio components (especially the core network) via network slicing is supposed to play a decisive role for the fulfillment of these QoS parameters in 5G. For the evaluation of various driving functions in the 5G context, BMW is cooperating with the Chair of Computer Networks and Communication Systems of the Friedrich-Alexander Universität Erlangen-Nürnberg (FAU) to set up a 5G V2X simulation environment during the upcoming year. The aim is to evaluate the performance as well as the limits of a 5G network with respect to V2X use cases in different realistic traffic scenarios and to investigate them in detail.
Published on 2018-12-19 14:52:22 (Permalink)
Three finished PhDs in two weeks!
Congratulations to our external PhD candidate Christina Stadler and our research assistants Vitali Schneider and David Steber: All three successfully defended their dissertations in the past two weeks! Their dissertations are titled:
- Christina Stadler: Ein effizientes Metamodell des Car2Car Kommunikationsaufkommens abhängig von der Umgebungstopologie
- Vitali Schneider: Stadardbasiertes Framework für die Testgetriebene Agile Simulation
- David Steber: Integration of Decentralized Battery Energy Storage Systems into the German Electrical Power System
Published on 2018-11-14 13:16:19 (Permalink)
Lecture at the Collegium Alexandrinum: Blockchain 2.0 and applications in decentralized energy supply
Staff member Jonas Schlund gave a lecture at the Collegium Alexandrinum on Blockchain 2.0 and applications in decentralized energy supply. The Collegium Alexandrinum informs the public inside and outside the university through events with reports from research and teaching at the Friedrich-Alexander-University Erlangen - Nuremberg. All lectures of the lecture block New IT Technologies are freely available in the video portal of the FAU.
Published on 2018-11-10 15:23:15 (Permalink)
Successful MMB 2018 in Erlangen
The 19th International GI/ITG Conference on “Measurement, Modelling and Evaluation of Computing Systems", organized by GI/ITG Technical Committee on "Measurement, Modelling and Evaluation of Computing Systems (MMB)" and the chair Computer Science 7 (Prof. R. German) was held from February 28th to February 28th, 2018 in Erlangen. Besides the regular scientific contributions, the program included three tutorials, two workshops, and invited scientific and industrial talks. With over 80 participants, the MMB 2018 in Erlangen is featured to be highly successful by the MMB spokesperson. Further information: https://www.mmb2018.de/
Published on 2018-05-02 14:28:50 (Permalink)
Doctoral candidate Jonas Schlund receives ZD.B-Fellowship
Computer Science 7 receives a prestigious grant. Staff member Jonas Schlund is now a Fellow of Centre Digitalization.Bavaria (ZD.B). By means of the Fellowships ten doctoral students with a pioneering research project in a topic relevant to digitization are funded financially and ideally. Funding includes the financing of a full position for up to three years as well as participation in the ZD. B Graduate Program. In a competitive selection process, Jonas Schlund and his doctoral project Decentralized organization of future energy systems based on the combination of blockchains and the cellular concept were selected from 142 applicants for one of the fellowships. On 1 and 2 February, the Graduate Program opened with an official KickOff event in Garching. More info here. © ZD.B | Paul Günther
Published on 2018-02-05 15:58:34 (Permalink)
Kolloquiumsvortrag: 09. Januar 2018, Jakob Hübler
Simulation und Modellierung von Aggregatoren verschiedener Kraft-werkstechnologien im deutschen Energiemarkt unter Einbeziehung zukünftiger EntwicklungsszenarienIm Rahmen der Weiterentwicklung eines Simulationsmodells zur Energiesystem-analyse des europäischen Energieversorgungssystems ist im Rahmen dieser Arbeit der blockscharfe Kraftwerkseinsatz für Deutschland unter Berücksichtigung von Kraftwerksrestriktionen (z.B. Mindestleistung, Mindestbetriebsdauern, Mindeststillstandzeiten, Teillastwirkungsgrade) mittels der Verwendung eines Optimierers in AnyLogic zu modellieren. Hierzu muss zunächst recherchiert werden, welche Kraftwerkseinsatzmodelle in der Literatur bereits existieren und welche Kosten zu berücksichtigen sind. Weiterführend soll die Abbildung der Aggregatoren einzelner Kraftwerksblöcke sowie entsprechender Börsenmechanismen inklusive der Abbildung von Unsicherheiten über die Verfügbarkeit von Kraftwerksblöcken sowie der Einspeisung aus erneuerbaren Energien erfolgen. Unter Einbeziehung öffentlich akzeptierter zukünftiger Entwicklungsszenarien (z.B. Netzentwicklungsplan) soll weiterhin die Notwendigkeit der Einbindung von großen Speichereinheiten in das Energieversorgungssystem analysiert werden. Ort: Raum 04.137, Martensstr. 3, Erlangen
Published on 2017-10-12 12:42:33 (Permalink)
Two accepted papers at VNC 2017
Both of our papers submitted to the IEEE Vehicular Network Conference 2017 to be held in Torino, Italy got accepted. The papers called "A Stochastic V2V LOS/NLOS Model Using Neural Networks for Hardware-In-The-Loop Testing" and "Multi-hop for GLOSA Systems: Evaluation and Results from a Field Experiment" are collaborations together with our external PhD students at AUDI Christina Stadler and Rainer Stahlmann as well as our alumnus David Eckhoff at TUMCREATE in Singapore. The conference is one of the most important platforms for the scientific exchange between researchers in the field of vehicular networks.
Published on 2017-10-10 04:10:12 (Permalink)
MMB 2018 in Erlangen
From February 26th until February 28th, 2018 the Chair Computer Science 7 organizes the 19th International GI/ITG Conference on Measurement, Modelling and Evaluation of Computing Systems (MMB 2018). Three workshops are planned covering the topics network calculus, smart cities, and social networks. Additionally, two special sessions will be organized focusing on SDN/NFV and Dependability in the IoT and Industry 4.0. Call for Papers and further information: http://www.mmb2018.de
Published on 2017-06-16 12:20:23 (Permalink)
Successful coorperation with thyssenkrupp
The Tech-Center Control Technology of the thyssenkrupp AG assigned Computer Science 7 to analyze the optimal dispatch of a cement plant by a combined optimization and simulation model. Mainly cost reduction potentials should be determined by optimizing the cement production considering the integration of storage within the whole production process. Furthermore, a redox-flow batterie and a wind powerplant were added to the cement plant in order to determine possible cost savings by reducing the grid power supply on the one hand and beeing able to offer frequency restoration reserve power on the other hand. The results showed that a significant decrease of electricity supply cost per produced ton cement is possible under certain conditions. For more detailed information please take a look at the paper presented at the Energieinformatik 2016 conference and the article in the technology magazine techforum published by thyssenkrupp AG.
Published on 2017-05-24 09:19:37 (Permalink)
5th GI/ITG KuVS Fachgespräch Inter-Vehicle Communication
The chair of Computer Science 7 (Computer Networks and Communication Systems) organized the 5th GI/ITG KuVS Fachgespräch Inter-Vehicle Communication (FG-IVC 2017), April 6-7 2017. Under the presence of a local television channel, numerous participants from the IVC-Community were initially inspired by a very interesting impulse speech by Dr. Sigfried Balleis (former mayor of the city of Erlangen and team member of the "German Innovation Lab"). Afterwards, young researchers have presented and discussed their current research topics. Further information: http://www7.cs.fau.de/fgivc2017
Published on 2017-04-03 18:11:28 (Permalink)
Open on AEG 2016
On September 11, 2016, the Energy Campus Nuremberg presented research projects and their applications at the "Open on AEG" event. The Chair of Computer Science 7 gave interested citizens an insight into the current research in the field of smart energy systems. With efficient simulation tools, energy systems are modeled from a single household to residential areas, distributed battery systems, industrial processes up to the entire electrical power supply. The efficiency potential for the use of renewable energy sources as well as of storage systems is determined and as a result an economic design is made possible. [metaslider id=1925]
Published on 2016-11-04 15:59:57 (Permalink)
Three papers at VNC 2016
The Chair Computer Science 7 for Computer Networks and Communication Systems is going to present three papers at this year's Vehicular Networking Conference (VNC 2016) in Columbus, Ohio. The conference is one of the most important platforms for the scientific exchange between researchers in the field of vehicular networks. The research team around David Eckhoff and Reinhard German will be presenting their work on the impact of antenna patterns on VANET simulations, a holistic approach to solve the location privacy problem in vehicular networks, and, in collaboration with Rainer Stahlmann from AUDI, new methods and results in the field of vehicle-to-traffic light communication. The conference will take place from 8th to 10th of December. More information can be found at http://www.ieee-vnc.org/.
Published on 2016-10-28 05:39:52 (Permalink)
Talk and Award at EnInnov 2016
Published on 2016-02-19 10:25:36 (Permalink)
Final steps of project e-NUE
The project e-NUE is now almost successfully completed. The objects of study of the second wave (AUDI A3 e-tron) have been already returned to the AUDI AG in September 2015. In the subsequent data analysis period, all developed computer models were successfully validated with regard to the behaviour of the real-world vehicles. At this moment, all relevant scientific results are subject to documentation. We want to express our thanks for three years of intensive and productive cooperation together with the AUDI AG and the N-ERGIE Aktiengesellschaft.
Published on 2016-02-03 16:03:39 (Permalink)
Presentation at Hannover Messe 2015 on 2015/04/15
As a leading energy research cooperation in Bavaria, the Energy Campus Nuremberg (EnCN) presents its activities in the field of energy research at the Hannover Messe (Hall 2, Stand A52 at the stand of Bayern Innovativ) to the visitors. The chair of computer science 7 is a part of the simulation group within the EnCN and involved in various research projects. On Wednesday (2015/04/15) representatives of Computer Sciencce 7 will present the research areas in the field of , Hybrid Simulation of connected intelligent Energy Systems'. For more information, please take a look at the attached flyer. Flyer i7 Hybride Simulation
Published on 2015-04-09 11:27:37 (Permalink)
14. GI/ITG KuVS Fachgespraech “Sensornetze”, September 23.-24.
Published on 2015-01-27 17:42:57 (Permalink)
KIT-Vortrag: “Techno-ökonomische Analsysen des zukünftigen Energiesystems”
Vortraege_KIT_26.01.2015 Zeit: Montag, 26. Januar 2015, 16:15 - 18:15 Uhr Ort: EnCN, "Auf AEG", Fürther Str. 250, Forum 2. OG, 90429 Nürnberg Infos und Anmeldung:
Published on 2015-01-21 12:24:35 (Permalink)
Klausur Informatik 1 für Nebenfachstudierende, 28. Januar 2015
Anmeldung bitte über Mein Campus bzw. das Prüfungsamt.
Published on 2014-12-01 15:59:02 (Permalink)
Project e-NUE: Handover of 2nd wave of vehicles
In the project e-NUE the second wave of electric vehicles will be handed over on 27 September 2014. 6 Audi A3 e-tron cars will be used in a field trial to test electric cars in commercial fleets.
Source: Stefan Bösl/AUDI AG
Source: Stefan Bösl/AUDI AG
Published on 2014-09-24 19:31:36 (Permalink)