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Mit längerfristigen Nutzerbefragungen in zwei unmittelbar benachbarten Bürogebäuden in Freiburg wurden das Temperaturempfinden der Nutzer und deren Zufriedenheit mit dem thermischen Raumkomfort zweimal täglich erfasst. Ein Bürogebäude wird im Sommer mit einem maschinellen Nachtlüftungskonzept konditioniert und das zweite verfügt über eine Betonkerntemperierung und eine Zu‐ und Abluftanlage. Auf Basis der vorhandenen Daten aus der Erhebung wurde mit Hilfe von Regressionsanalysen ein Modell zur Vorhersage der Komforttemperatur berechnet und mit den Modellen in DIN EN 15251 verglichen.
Die Energiewende ist ein elementares Thema, für Deutschland wie auch für viele andere Regionen weltweit. Bei der Bereitstellung effizienter und stabiler Verteilnetze stellen Kommunikationslösungen einen zentralen Baustein dar, um auf der Grundlage eines zeitnahen Monitorings koordinierte Regelalgorithmen zu realisieren. Dies gilt für alle Ebenen der Versorgung, wobei aus Sicht der Kommunikationstechnik die unterste Ebene der Verteilnetze am interessantesten ist: Hier sind die anspruchsvollsten Anforderungen im Hinblick auf die Kosten- und die Energieoptimierung der Kommunikationsknoten sowie die Administrierbarkeit, die Stabilität und die Skalierbarkeit der Gesamtlösung zu berücksichtigen. Das Steinbeis-Transferzentrum Embedded Design und Networking an der Hochschule Offenburg unter der Leitung von Prof. Dr.-Ing. Axel Sikora hat in verschiedenen Projekten mit renommierten Partnern umfangreiche Lösungen für diese sogenannte Primärkommunikation entwickelt.
Automatic Meter Reading (AMR) is a major enabler for the upcoming smart grid. Potentially, it will be one of the first really large-scale M2M-communication solutions for sensor applications.
To date, the definition of the standardized communication stacks for Local Metrological Network (LMN) in AMR is still ongoing. This holds true both for ZigBee Smart Energy Profile and for Wireless M-Bus according to EN 13757. During this process, there is the necessity for flexible, albeit optimized solutions, which support the different existing and upcoming versions of the communication protocols. In the case of Wireless M-Bus, the major contender for European and possibly Asian installations, this is valid not only for the different operation modes (C-, N-, P-, Q-, R-, S-, and T-modes), which work in different frequencies (i.e. 868 MHz, 433 MHz, and 169 MHz) but also for the application layer, where additional bodies, like EN137575, Open Metering System (OMS) Group, or national bodies follow their approaches.
This contribution describes requirements, design techniques and experiences from the development of highly efficient Wireless M-Bus protocol stacks with support of good flexibility and portability between microcontroller platforms and RF-transceivers. The presented approach is not limited to the use of modern software engineering design processes, as such, but also includes essential additional features like testing or simulation, as well as tools for commissioning and monitoring.
Ranging errors are inevitable in all local positioning systems, including those based on Time-of-Flight (ToF) technique. Results of experiments show that the major cause for these errors is a signal degradation from multipath propagation. This effect is especially critical in case of Non-Light-of-Sight (NLOS) conditions. This paper describes causes that affects ranging errors for nanoLOC™-TOF-technology and presents estimations for the probability density functions of such errors under different NLOS conditions. The provided estimations allow the improvement of the accuracy of the localization through the subsequent mitigation of the ranging errors from the measurements. Additionally, it is proposed to increase the number of cases of NLOS-conditions for the improvement of the accuracy.
Efficient, low-cost, secure and reliable communication solutions are a major stepping stone for smart metering and smart grid applications. This especially holds true for the so called primary communication or local metrological network (LMN) between a local meter or actuator and a data collector or gateway, where the highest requirements with regard to cost, bandwidth, and energy efficiency have to be taken into consideration. Multiple developments and field tests are going on in this field, however, energy autarkic devices are hardly found, yet.
The communication technologies for automatic me-ter reading (smart metering) and for energy production and distribution networks (smart grid) have the potential to be one of the first really highly scaled machine-to-machine-(M2M)-applications. During the last years two very promising devel-opments around the wireless part of smart grid communication were initialized, which possibly have an impact on the markets far beyond Europe and far beyond energy automation. Besides the specifications of the Open Metering System (OMS) Group, the German Federal Office for Information Security (Bundesamt für Sicherheit in der Informationstechnik, BSI) has designed a protection profile (PP) and a technical directive (TR) for the communication unit of an intelligent measurement sys-tem (smart meter gateway), which were released in March 2013. This design uses state-of-the-art technologies and prescribes their implementation in real-life systems. At first sight the expenditures for the prescribed solutions seem to be significant. But in the long run, this path is inevitable and comes with strategic advantages.
Efficient, low-cost, secure and reliable communication solutions are a major stepping stone for smart metering and smart grid applications. This especially holds true for the so called primary communication or local metrological network (LMN) between a local meter or actuator and a data collector or gateway, where the highest requirements with regard to cost, bandwidth, and energy efficiency have to be taken into consideration. Multiple developments and field tests are going on in this field, however, energy autarkic devices are hardly found, yet. This contribution describes the development of an automatic water meter reading (AWMR) technology based on Wireless M-Bus to provide water utility companies with an automatic remote water meter reading solution. It addresses the special needs of home utilities by providing a remote metering solution independent from the electricity infrastructure, both in terms of data communication and in terms of power supply. For this project, a cost efficient integrated energy harvesting system powered by the available water flow was developed, to enable operation independently of the mains grid, and eliminate the need for battery replacement for near-zero maintenance costs.
The communication technologies for automatic meter reading (smart metering) and for energy production and distribution networks (smart grid) have the potential to be one of the first really highly scaled machine-to-machine-M2M-applications. During the last years, two very promising developments around the wireless part of the smart grid communication were initialized, which possibly could have an impact on the network architectures and the markets far beyond Germany and far beyond energy automation. Besides the specification of the OMS Group of a security extension to the Wireless M-Bus protocol (EN13757-4), the German Federal Office for Information Security (Bundesamt für Sicherheit in der Informationstechnik, BSI) has designed a Protection Profile (PP) and a Technical Directive (TR) for the communication unit of an intelligent measurement system (Smart Meter Gateway), which were released in March 2013. This design uses state of the art technologies and prescribes their implementation in real-life systems. At first, the proposed paper will present the most important characteristics of this architecture. It will then give an insight into the implementation of the OMS security protocols, which imply the usage of a mutually authenticated SSL protocol also in the Local Metrological Network. This is achieved with the help of an additional Authentication and Fragmentation Layer (AFL). This secure communication will be terminated in a BSI conformant secure smart meter gateway, which is developed in a different project and described in the second step. Finally, the contribution will discuss the integration of such a metering network into an overall telecommunication network and PKI infrastructure.
A Localization System Using Inertial Measurement Units from Wireless Commercial Handheld Devices
(2013)
This paper describes a newly developed technology for the calculation of trajectories of mobile objects, which is based on commercially available sensors being integrated into modern mobile phones and other gadgets. First, a step counting technique was implemented. Second, a novel step length estimator is proposed. These two algorithms utilize the data from accelerometer sensor only. Third, the heading information was obtained using a gyroscope with complementary filter in quaternion form. The combined algorithm was implemented on a low-power ARM processor to provide the trajectory points relative to an initial point. The proposed technique was tested by 10 subjects, in different shoes with different paces. The dependence of the performance of the technology on the attaching point of the mobile device is weak. The proposed algorithms have better balance and estimation accuracy and depend in less degree on the variety in physical parameters of people in comparison with the existing techniques. In experiments inertial measurement units were mounted in different places, i.e. in the hand, in trousers or in T-shirt pockets. The return position error did not exceed 5% of the total travelled distance for all performed tests.
A highly scalable IEEE802.11p communication and localization subsystem for autonomous urban driving
(2013)
The IEEE802.11p standard describes a protocol for car-to-X and mainly for car-to-car-communication. It has found its place in hardware and firmware implementations and is currently tested in various field tests. In the research project Ko-TAG, which is part of the research initiative Ko-FAS, cooperative sensor technology is developed for the support of highly autonomous driving. A secondary radar principle based on communication signals enables localization of objects with simultaneous data transmission. It mainly concentrates on the detection of pedestrians and other vulnerable road users (VRU), but also supports pre crash safety applications. Thus it is mainly targeted for the support of traffic safety applications in intra-urban scenarios. This contribution describes the Ko-TAG part of the overall initiative, which develops a subsystem to improve the real-time characteristics of IEEE802.11p needed for precise time of flight real-time localization. In doing this, it still fits into the regulatory schemes. It discusses the approach for definition and verification of the protocol design, while maintaining the close coexistence with existing IEEE802.11p subsystems. System simulations were performed and hardware was implemented. Test results are shown in the last part of the paper.
Multi-agent systems are a subject of continuously increasing interest in applied technical sciences. Smart grids are one evolving field of application. Numerous smart grid projects with various interpretations of multi-agent systems as new control concept arose in the last decade. Although several theoretical definitions of the term ‘agent’ exist, there is a lack of practical understanding that might be improved by clearly distinguishing the agent technologies from other state-of-the-art control technologies. In this paper we clarify the differences between controllers, optimizers, learning systems, and agents. Further, we review most recent smart grid projects, and contrast their interpretations with our understanding of agents and multi-agent systems. We point out that multi-agent systems applied in the smart grid can add value when they are understood as fully distributed networks of control entities embedded in dynamic grid environments; able to operate in a cooperative manner and to automatically (re-)configure themselves.
Unter dem europäischen Programm Intelligent Energy for Europe (IEE) fanden sich acht europäische Partner zusammen, um im Rahmen des Projektes ThermCo Lüftungs‐ und Kühlenergiekonzepte für Nichtwohngebäude mit niedrigem Energieeinsatz im Hinblick auf die Energieeffizienz und den thermischen Raumkomfort zu bewerten (siehe Teil 1 dieser Veröffentlichung in Bauphysik 34 (2012), Heft 6. Mit Hilfe einer Simulationsstudie für ein typisches Bürogebäude wird das Potenzial unterschiedlicher Lüftungs‐ und Kühlstrategien unter Berücksichtigung von Energieeffizienz und Raumkomfort für verschiedene europäische Klimazonen bewertet. Die Ergebnisse weisen eine hohe Wirksamkeit von Nachtlüftungskonzepten im nord‐europäischen Sommerklima mit verhältnismäßig niedrigen Außentemperaturen nach. Im mitteleuropäischen Sommerklima bietet das Erdreich ein ausreichend niedriges Temperaturniveau für den effizienten Einsatz von wassergeführten Flächentemperiersystemen. Im südeuropäischen Sommerklima kann eine aktive Kühlung über Luft die hohen und schnell fluktuierenden Kühllasten effizient abführen.
Transösophageales interventrikuläres Delay bei Vorhofflimmern und kardialer Resynchronisation
(2013)
Die transösophageale linksventrikuläre Elektrokardiographie ermöglicht die Evaluierung der elektrischen ventrikulären Desynchronisation im Rahmen der kardialen Resynchronisationstherapie der Herzinsuffizienz. Das Ziel der Untersuchung besteht in der präoperativen Abschätzung des transösophagealen interventrikulären Delays bei Vorhofflimmern und kardialer Resynchronisationstherapie. Bei Patienten mit Vorhofflimmern, Herzinsuffizienz New York Heart Association Klasse 3,0 ± 0,2 und QRS-Dauer 159,6 ± 23,9 ms wurde das fokusierte transösophageale linksventrikuläre EKG abgeleitet. Die kardiale Resynchronisationstherapie Responder QRS-Dauer korrelierte mit dem transösophagealen interventrikulären Delay bei Vorhofflimmern.
Das Ausmaß der elektrischen ventrikulären Desynchronisation bei reduzierter linksventrikulärer Funktion ist von Bedeutung für den Erfolg der Resynchronisationstherapie der Herzinsuffizienz mit biventrikulärer Stimulation. Das Ziel der Untersuchung besteht in der nichtinvasiven Messung der elektrischen inter-ventrikulären Desynchronisation mit und ohne ischämische Herzerkrankung bei kardialen Resynchronisationstherapie Respondern. Bei Patienten mit 25,3 ± 7,3 % reduzierter linksventrikulärer Ejektionsfraktion und 166,9 ± 38,5 ms QRS-Dauer wurde das transösophageale linksventrikuläre EKG abgeleitet. Die QRS-Dauer korrelierte mit dem interventrikulären und links-ventrikulären Delay bei Resynchronisationstherapie Respondern mit nicht-ischämischer Herzerkrankung.
Decrease of non-responder rate is the main chal-lenge in cardiac resynchronization therapy. The problem could be solved, partly, in the follow-up by consequent indi-vidualization of hemodynamic pacing parameters. The eso-phageal electrogram feature of the Biotronik ICS 3000 programmer was used in the follow-up of 20 heart failure patients carrying implants for cardiac resynchronization therapy. Adverse hemodynamic programming of the sensed and paced AV delay could be easily observed and replaced by the individual optimal duration in 3 patients (15%) VDD and DDD operation.This result proves the value of esophageal electrogram recording CRT follow-up.
In this paper we present a model of the discharge of a lithium–oxygen battery with aqueous electrolyte. Lithium–oxygen batteries (Li–O2) have recently received great attention due to their large theoretical specific energy. Advantages of the aqueous design include the stability of the electrolyte, the long experience with gas diffusion electrodes (GDEs), and the solubility of the reaction product lithium hydroxide. However, competitive specific energies can only be obtained if the product is allowed to precipitate. Here we present a dynamic one-dimensional model of a Li–O2 battery including a GDE and precipitation of lithium hydroxide. The model is parameterized using experimental data from the literature. We demonstrate that GDEs remove power limitations due to slow oxygen transport in solutions and that lithium hydroxide tends to precipitate on the anode side. We discuss the system architecture to engineer where nucleation and growth predominantly occurs and to optimize for discharge capacity.
Compact solid discharge products enable energy storage devices with high gravimetric and volumetric energy densities, but solid deposits on active surfaces can disturb charge transport and induce mechanical stress. In this Letter, we develop a nanoscale continuum model for the growth of Li2O2 crystals in lithium–oxygen batteries with organic electrolytes, based on a theory of electrochemical nonequilibrium thermodynamics originally applied to Li-ion batteries. As in the case of lithium insertion in phase-separating LiFePO4 nanoparticles, the theory predicts a transition from complex to uniform morphologies of Li2O2 with increasing current. Discrete particle growth at low discharge rates becomes suppressed at high rates, resulting in a film of electronically insulating Li2O2 that limits cell performance. We predict that the transition between these surface growth modes occurs at current densities close to the exchange current density of the cathode reaction, consistent with experimental observations.
In the dual membrane fuel cell (DM-Cell), protons formed at the anode and oxygen ions formed at the cathode migrate through their respective dense electrolytes to react and form water in a porous composite layer called dual membrane (DM). The DM-Cell concept was experimentally proven (as detailed in Part I of this paper). To describe the electrochemical processes occurring in this novel fuel cell, a mathematical model has been developed which focuses on the DM as the characteristic feature of the DM-Cell. In the model, the porous composite DM is treated as a continuum medium characterized by effective macro-homogeneous properties. To simulate the polarization behavior of the DM-Cell, the potential distribution in the DM is related to the flux of protons and oxygen ions in the conducting phases by introducing kinetic and transport equations into charge balances. Since water pressure may affect the overall formation rate, water mass balances across the DM and transport equations are also considered. The satisfactory comparison with available experimental results suggests that the model provides sound indications on the effects of key design parameters and operating conditions on cell behavior and performance.
Der Einbau von Smart Metern und deren intelligente Vernetzung in Richtung eines Smart Grid wird Stromverbrauchsmuster bis in die Haushalte hinein verändern. Über die technisch geprägte Diskussion um die Komponenten dafür darf deshalb keinesfalls die Einbeziehung der Gesellschaft in den anstehenden Wandel vergessen werden. Transparenz bei den Kosten, die Förderung von Vertrauen insbesondere in die Datenschutzstandards und eine verständliche Aufklärungsarbeit sind Schlüssel für den notwendigen Dialog zwischen Energieversorgern, Politik und Bürgern.
Modeling and Simulation the Influence of Solid Carbon Formation on SOFC Performance and Degradation
(2013)
The combination of fossil-derived fuels with ethanol and methanol has acquired relevance and attention in several countries in recent years. This trend is strongly affected by market prices, constant geopolitical events, new sustainability policies, new laws and regulations, etc. Besides bio-fuels these materials also include different additives as anti-shock agents and as octane enhancer. Some of the chemical compounds in these additives may have harmful properties for both environment and public health (besides the inherent properties, like volatility). We present detailed Raman spectral information from toluene (C7H8) and ethanol (C2H6O) contained in samples of ElO gasoline-ethanol blends. The spectral information has been extracted by using a robust, high resolution Fourier-Transform Raman spectrometer (FT-Raman) prototype. This spectral information has been also compared with Raman spectra from pure additives and with standard Raman lines in order to validate its accuracy in frequency. The spectral information is presented in the range of 0 cm-1 to 3500 cm-1 with a resolution of 1.66cm-1. This allows resolving tight adjacent Raman lines like the ones observed around 1003cm-1 and 1030cm-1 (characteristic lines of toluene). The Raman spectra obtained show a reduced frequency deviation when compared to standard Raman spectra from different calibration materials. The FT-Raman spectrometer prototype used for the analysis consist basically of a Michelson interferometer and a self-designed photon counter cooled down on a Peltier element arrangement. The light coupling is achieved with conventional62.5/125μm multi-mode fibers. This FT-Raman setup is able to extract high resolution and frequency precise Raman spectra from the additives in the fuels analyzed. The proposed prototype has no additional complex hardware components or costly software modules. The mechanical and thermal disturbances affecting the FT-Raman system are mathematically compensated by accurately extracting the optical path information of the Michelson interferometer. This is accomplished by generating an additional interference pattern with a λ = 632.8 nm Helium-Neon laser (HeNe laser). It enables the FT-Raman system to perform reliable and clean spectral measurements from the materials under observation.
Die von der Bundesregierung beschlossene Energiewende stellt Politik und Gesellschaft, Wirtschaft und Wissenschaft vor große Herausforderungen. Entscheidend für den Erfolg der Energiewende wird es sein, die Wettbewerbsfähigkeit des Industriestandortes Deutschland zu erhalten. Dafür muss weiterhin eine hohe Stromversorgungsqualität bei zugleich international wettbewerbsfähigen Strompreisen sichergestellt sein. Der BDI stellt fünf Prinzipien auf dem Weg zu einem neuen Strommarktdesign auf und zeigt, dass eine informations- und kommunikationstechnische Vernetzung relevanter Komponenten des Energiesystems für das künftige System essenziell ist.
Statt MOOC
(2013)
Die Weltwirtschaftskrise 2008 hat mit ihrer zeitweisen Verknappung von Acetonitril eindringlich gezeigt, dass man nicht nur auf eine einzige chromatographische Methode setzten sollte. Genau dies wird aber im Augenblick getan, denn Industrie und Forschung setzen mehrheitlich auf die High Performance Liquid Chromatography (HPLC) als die Trennmethode ihrer Wahl. Für viele Anwendungen in der Pharmazie, in der Umweltanalytik, der Lebensmittelanalytik, aber auch in der Inprozesskontrolle gibt es mit der Dünnschichtchromatografie eine Alternative.