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Introduction: Despite lots of developments in the last years, radiofrequency ablation of rhythm diseases is a safe but still complex procedure that requires special experience and expertise of the physicians and biomedical engineers. Thus, there is a need of special trainings to become familiar with the different equipment and to explain several effects that can be observed during clinical routine.
Methods: The Offenburg University of Applied Sciences offers a biomedical engineering study path specialized in the fields of cardiology, electrophysiology and cardiac electronic implants. It`s Peter Osypka Institute for Pacing and Ablation provides teaching following the slogan “Learning by watching, touching and adjusting”. It conducts lots of trainings for students as well as young physicians interested in electrophysiology and radiofrequency ablation.
Results: In-vitro trainings will be provided using the Osypka HAT 200 and HAT300s, Stockert EPshuttle and SmartAblate system as well as the Boston EPT-1000XP and Maestro 3000 and the Radionics RFG-3E cardiac radio frequency ablation generators. All of them require different handling as well as special accessories like catheter connection cables or boxes and back plates. The participants will be trained in the setup of temperature, power and cut-off impedance dependent on different ablation catheters. Furthermore troubleshooting in hard- and software is part of the program. Performing procedures in pork or animal protein and using physiological saline solution to simulate the blood flow, they can study the influence of contact force and impedance on lesion geometry etc. and to avoid adverse effects like “plops”. Lots of catheter types are available: 4mm tip, 8mm standard and gold tip, open and closed irrigated tip ablation catheters of different companies. The experiments will be completed by measuring the lesion size dependent on the used catheter type and ablation settings.
Conclusion: In-vitro training in radiofrequency ablation is a challenge for biomedical engineering students and young physicians.
Introduction: Patient selection for cardiac resynchronization therapy (CRT) requires quantification of left ventricular conduction delay (LVCD). After implantation of biventricular pacing systems, individual AV delay (AVD) programming is essential to ensure hemodynamic response. To exclude adverse effects, AVD should exceed individual implant-related interatrial conduction times (IACT). As result of a pilot study, we proposed the development of a programmer-based transoesophageal left heart electrogram (LHE) recording to simplify both, LVCD and IACT measurement. This feature was implemented into the Biotronik ICS3000 programmer simultaneously with 3-channel surface ECG.
Methods: A 5F oesophageal electrode was perorally applied in 44 heart failure CRT-D patients (34m, 10f, 65±8 yrs., QRS=162±21ms). In position of maximum left ventricular deflection, oesophageal LVCD was measured between onsets of QRS in surface ECG and oesophageal left ventricular deflection. Then, in position of maximum left atrial deflection (LA), IACT in VDD operation (As-LA) was calculated by difference between programmed AV delay and the measured interval from onset of left atrial deflection to ventricular stimulus in the oesophageal electrogram. IACT in DDD operation (Ap-LA) was measured between atrial stimulus and LA..
Results: LVCD of the CRT patients was characterized by a minimum of 47ms with mean of 69±23ms. As-LA and Ap-LA were found to be 41±23ms and 125±25ms, resp., at mean. In 7 patients (15,9%), IACT measurement in DDD operation uncovered adverse AVD if left in factory settings. In this cases, Ap-LA exceeded the factory AVD. In 6 patients (13,6%), IACT in VDD operation was less than or equal 10ms indicating the need for short AVD.
Conclusion: Response to CRT requires distinct LVCD and AVD optimization. The ICS3000 oesophageal LHE feature can be utilized to measure LVCD in order to justify selection for CRT. IACT measurement simplifies AV delay optimization in patients with CRT systems irrespective of their make and model.
In-vivo and in-vitro comparison of implant-based CRT optimization - What provide new algorithms?
(2011)
Introduction: In cardiac resynchronization therapy (CRT), individual AV delay (AVD) optimization can effectively increase hemodynamics and reduce non-responder rate. Accurate, automatic and easily comprehensible algorithms for the follow-up are desirable. QuickOpt is the first attempt of a semi-automatic intracardiac electrogram (IEGM) based AVD algorithm. We aimed to compare its accuracy and usefulness by in-vitro and in-vivo studies.
Methods: Using the programmable ARSI-4 four-chamber heart rhythm and IEGM simulator (HKP, Germany), the QuickOpt feature of an Epic HF system (St. Jude, USA) was tested in-vitro by simulated atrial IEGM amplitudes between 0.3 and 3.5mV during both, manual and automatic atrial sensing between 0.2 and 1.0mV. Subsequently, in 21 heart failure patients with implanted biventricular defibrillators, QuickOpt was performed in-vivo. Results of the algorithm for VDD and DDD stimulation were compared with echo AV delay optimization.
Results: In-vitro simulations demonstrated a QuickOpt measuring accuracy of ± 8ms. Depending on atrial IEGM amplitude, the algorithm proposed optimal AVD between 90 and 150ms for VDD and between 140 and 200ms for DDD operation, respectively. In-vivo, QuickOpt difference between individual AVD in DDD and VDD mode was either 50ms (20pts) or 40ms (1pt). QuickOpt and echo AVD differed by 41 ± 25ms (7 – 90ms) in VDD and by 18 ± 24ms (17-50ms) in DDD operation. Individual echo AVD difference between both modes was 73 ± 20ms (30-100ms).
Conclusion: The study demonstrates the value of in-vitro studies. It predicted QuickOpt deficiencies regarding IEGM amplitude dependent AVD proposals constrained to fixed individual differences between DDD and VDD mode. Consequently, in-vivo, the algorithm provided AVD of predominantly longer duration than echo in both modes. Accepting echo individualization as gold standard, QuickOpt should not be used alone to optimize AVD in CRT patients.
Introduction: To simplify AV delay (AVD) optimization in cardiac resynchronization therapy (CRT), we reported that the hemodynamically optimal AVD for VDD and DDD mode CRT pacing can be approximated by individually measuring implant-related interatrial conduction intervals (IACT) in oesophageal electrogram (LAE) and adding about 50ms. The programmer-based St Jude QuickOpt algorithm is utilizing this finding. By automatically measuring IACT in VDD operation, it predicts the sensed AVD by adding either 30ms or 60ms. Paced AVD is strictly 50ms longer than sensed AVD. As consequence of those variations, several studies identified distinct inaccuracies of QuickOpt. Therefore, we aimed to seek for better approaches to automate AVD optimization.
Methods: In a study of 35 heart failure patients (27m, 8f, age: 67±8y) with Insync III Marquis CRT-D systems we recorded telemetric electrograms between left ventricular electrode and superior vena cava shock coil (LVtip/SVC = LVCE) simultaneously with LAE. By LVCE we measured intervals As-Pe in VDD and Ap-Pe in DDD operation between right atrial sense-event (As) or atrial stimulus (Ap), resp., and end of the atrial activity (Pe). As-Pe and Ap-Pe were compared with As-LA an Ap-LA in LAE, respectively.
Results: End of the left atrial activity in LVCE could clearly be recognized in 35/35 patients in VDD and 29/35 patients in DDD operation. We found mean intervals As-LA of 40.2±24.5ms and Ap-LA of 124.3±20.6ms. As-Pe was 94.8±24.1ms and Ap-Pe was 181.1±17.8ms. Analyzing the sums of As-LA + 50ms with duration of As-Pe and Ap-LA + 50ms with duration of Ap-Pe, the differences were 4.7±9.2ms and 4.2±8.6ms, resp., only. Thus, hemodynamically optimal timing of the ventricular stimulus can be triggered by automatically detecting Pe in LVCE.
Conclusion: Based on minimal deviations between LAE and LVCE approach, we proposed companies to utilize the LVCE in order to automate individual AVD optimization in CRT pacing.
Message co chairmen
(2017)
Energy and environment continue to be major issues of human mankind. This holds true on the regional, the national, and the global level. And it is one of the problems, where engineers and scientists in conjunction with political will and people's awareness, can find new approaches and solutions to save the natural resources and to make their use more efficient.
The paper proposes a system architecture for charging infrastructure that serves the requirements of future fleets of shared-use electric vehicles in urban scenarios. The focus of the development is on the interfaces to central stakeholders such as mobility service providers, distribution network operators and utilities. The main concept of the proposed system is the adherence to a stringent resource-oriented design approach, following the design principles of the Representational State Transfer (REST) architectural software style for distributed systems. This design approach is used from the cloud-based services down to the implementation of the charging infrastructure's control algorithms. Focusing on the resources of the various entities simplifies the implementation of their interactions, compared to the explicit declaration of services that are available. The system design ensures that the charging infrastructure is open to all users and generates a benefit beyond basic charging operations. Integration in emerging smart markets is done via open web-based interfaces. These allow for the generation of an added value of concrete services for shared-use electric mobility. A link to the field of grid operation is proposed using the ISO/IEC 61850 telecontrol standard. The smart meter capabilities of the charging stations can be used to gain additional information on the current state of the distribution grid. As an exemplary service a load management service for a fleet of shared-use electric vehicles is going to be implemented.
Multi-phase management is crucial for performance and durability of electrochemical cells such as batteries and fuel cells. In this paper we present a generic framework for describing the two-dimensional spatiotemporal evolution of gaseous, liquid and solid phases, as well as their interdependence with interfacial (electro-)chemistry and microstructure in a continuum description. The modeling domain consists of up to seven layers (current collectors, channels, electrodes, separator/membrane), each of which can consist of an arbitrary number of bulk phases (gas, liquid, solid) and connecting interfaces (two-phase or multi-phase boundaries). Bulk and interfacial chemistry is described using global or elementary kinetic reactions. Multi-phase management is coupled to chemistry and to mass and charge transport within bulk phases. The functionality and flexibility of this framework is demonstrated using four application areas in the context of post-lithium-ion batteries and fuel cells, that is, lithium-sulfur (Li-S) cells, lithium-oxygen (Li-O) cells, solid oxide fuel cells (SOFC) and polymer electrolyte membrane fuel cells (PEFC). The results are compared to models available in literature and properties of the generic framework are discussed.
A theoretical description is given for the propagation of surface acoustic wave pulses in anisotropic elastic media subject to the influence of nonlinearity. On the basis of nonlinear elasticity theory, an evolution equation is presented for the surface slope or the longitudinal surface velocity associated with an acoustic pulse. It contains a non-local nonlinearity, characterized by a kernel that strongly varies from one propagation geometry to another due to the anisotropy of the substrate. It governs pulse shape evolution in homogeneous halfspaces and the shapes of solitary surface pulses that exist in coated substrates. The theory describing nonlinear Rayleigh-type surface acoustic waves is extended in a straightforward way to surface waves that are localized at a one-dimensional acoustic waveguide like elastic wedges.
The Division Industrial Chemistry of the Swiss Chemical Society organizes periodically a two-day event for the post-graduate education of its members. This event is known as the Freiburger Symposium. This year it focussed on sustainable chemical production. The twelve talks covered the following aspects: ethical needs for sustainability standards, the required, attained, and yet to be attained sustainability goals in chemical industry. Diverse case studies showed the highly developed awareness about the sustainability issue within the chemical community.
The importance of obtaining simultaneous particle size and concentration values has grown up with continuing discussion of the health effects, of internal combustion engine generated particulate emissions and in particular of Diesel soot emissions. In the present work an aerosol measurement system is described that delivers information about particle size and concentration directly from the undiluted exhaust gas.
Using three laser diodes of different wavelengths which form one parallel light beam, each spectral attenuation is analysed by a single detector and the particle diameter and concentration is evaluated by the use of the Mie theory and shown on-line at a frequency of 1 Hz. The system includes an optical long-path-cell (White principle) with an adjustable path length from 2.5 to 15 m, which allows the analysis within a broad concentration range.
On-line measurements of the particulate emissions in the hot, undiluted exhaust of Diesel engines are presented under stationary and transient engine’s load conditions. Mean particle diameters well below 100 nm are detected for modern Diesel engines. The measured particle concentration corresponds excellently with the traditional gravimetrical measurements of the diluted exhaust. Additionally, measurements of particle emissions (mostly condensed hydricarbons) from a two-stroke engine are presented and discussed.
In this paper, we establish a simple model for the exchange of messages in a vehicular network and we consider fundamental limits on the achievable data rate. For a vehicular network, the exchange of data with other nearby vehicles is particularly important for traffic safety, e.g. for collision avoidance, but also for cooperative applications like platooning. These use cases are currently addressed by standards building on IEEE 802.11p, namely ITS-G5 and DSRC (dedicated short range communication), which encounter saturation problems at high vehicle densities. For this reason, we take a step back and ask for the fundamental limits for the common data rate in a vehicular network. After defining a simple single-lane model and the corresponding capacity limits for some basic multiple- access schemes, we present results for a more realistic setting. For both scenarios, non-orthogonal multiple-access (NOMA) yields the best results.
This paper evaluates the implementation of Medium Access Control (MAC) protocols suitable for massive access connectivity in 5G multi-service networks. The access protocol extends multi-packet detection receivers based on Physical Layer Network Coding (PLNC) decoding and Coded Random Access protocols considering practical aspects to implement one-stage MAC protocols for short packet communications in mMTC services. Extensions to enhance data delivery phase in two- stage protocols are also proposed. The assessment of the access protocols is extended under system level simulations where a suitable link to system interface characterization has been taken into account.
This paper is discussing the development of a wireless Indoor Smart Gardening System with the focus on energy autonomous working. The Smart Gardening System, which is presented in this paper consists of a network of energy autonomous wireless sensor nodes which are used for monitoring important plant parameters like air temperature, soil moisture, pressure or humidity and in future to control an actuator for the plant irrigation and to measure further parameter as light and fertilizer level. Solar energy harvesting is used for powering the wireless nodes without the usage of a battery. Comparable Smart Gardening Systems are usually battery-powered. Furthermore, the overall Smart Gardening System consists of a battery powered gateway based on a Raspberry Pi 3 system, which controls the wireless nodes and collects their sensor data. The gateway is able to send the information to an internet server application and via Wi-Fi to mobile devices. Particularly the architecture of the energy autonomous wireless nodes will be considered because fully energy autonomous wireless networks could not be implemented without special concepts for the energy supply and architecture of the wireless nodes.
Optische Navigationssysteme weisen bisher eine eindeutige Trennung zwischen nachverfolgendem Gerät (Tool Tracker) und nachverfolgten Geräten (Tracked Tools) auf. In dieser Arbeit wird ein neues Konzept vorgestellt, dass diese Trennung aufhebt: Jedes Tracked Tool ist gleichzeitig auch Tool Tracker und besteht aus Marker-LEDs sowie mindestens einer Kamera, mit deren Hilfe andere Tracker in Lage und Orientierung nachverfolgt werden können. Bei Verwendung von nur einer Kamera geschieht dies mittels Pose Estimation, ab zwei Kameras werden die Marker-LEDs trianguliert. Diese Arbeit beinhaltet die Vorstellung des neuen Peer-To-Peer-Tracking-Konzepts, einen sehr schnellen Pose-Estimation-Algorithmus für beliebig viele Marker sowie die Klärung der Frage, ob die mit Pose Estimation erreichbare Genauigkeit vergleichbar mit der eines Stereo-Kamera-Systems ist und den Anforderungen an die chirurgische Navigation gerecht wird.
The CAN bus still is an important fieldbus in various domains, e.g. for in-car communication or automation applications. To counter security threats and concerns in such scenarios we design, implement, and evaluate the use of an end-to-end security concept based on the Transport Layer Security protocol. It is used to establish authenticated, integrity-checked, and confidential communication channels between field devices connected via CAN. Our performance measurements show that it is possible to use TLS at least for non time-critical applications, as well as for generic embedded networks.
Uncontrollable manufacturing variations in electrical hardware circuits can be exploited as Physical Unclonable Functions (PUFs). Herein, we present a Printed Electronics (PE)-based PUF system architecture. Our proposed Differential Circuit PUF (DiffC-PUF) is a hybrid system, combining silicon-based and PE-based electronic circuits. The novel approach of the DiffC-PUF architecture is to provide a specially designed real hardware system architecture, that enables the automatic readout of interchangeable printed DiffC-PUF core circuits. The silicon-based addressing and evaluation circuit supplies and controls the printed PUF core and ensures seamless integration into silicon-based smart systems. Major objectives of our work are interconnected applications for the Internet of Things (IoT).
Vehicle-to-Everything (V2X) communication promises improvements in road safety and efficiency by enabling low-latency and reliable communication services for vehicles. Besides using Mobile Broadband (MBB), there is a need to develop Ultra Reliable Low Latency Communications (URLLC) applications with cellular networks especially when safety-related driving applications are concerned. Future cellular networks are expected to support novel latencysensitive use cases. Many applications of V2X communication, like collaborative autonomous driving requires very low latency and high reliability in order to support real-time communication between vehicles and other network elements. In this paper, we classify V2X use-cases and their requirements in order to identify cellular network technologies able to support them. The bottleneck problem of the medium access in 4G Long Term Evolution(LTE) networks is random access procedure. It is evaluated through simulations to further detail the future limitations and requirements. Limitations and improvement possibilities for next generation of cellular networks are finally detailed. Moreover, the results presented in this paper provide the limits of different parameter sets with regard to the requirements of V2X-based applications. In doing this, a starting point to migrate to Narrowband IoT (NB-IoT) or 5G - solutions is given.
The next generation cellular networks are expected to improve reliability, energy efficiency, data rate, capacity and latency. Originally, Machine Type Communication (MTC) was designed for low-bandwidth high-latency applications such as, environmental sensing, smart dustbin, etc., but there is additional demand around applications with low latency requirements, like industrial automation, driver-less cars, and so on. Improvements are required in 4G Long Term Evolution (LTE) networks towards the development of next generation cellular networks for providing very low latency and high reliability. To this end, we present an in-depth analysis of parameters that contribute to the latency in 4G networks along with a description of latency reduction techniques. We implement and validate these latency reduction techniques in the open-source network simulator (NS3) for narrowband user equipment category Cat-Ml (LTE-M) to analyze the improvements. The results presented are a step towards enabling narrowband Ultra Reliable Low Latency Communication (URLLC) networks.
The excessive control signaling in Long Term Evolution networks required for dynamic scheduling impedes the deployment of ultra-reliable low latency applications. Semi-persistent scheduling was originally designed for constant bit-rate voice applications, however, very low control overhead makes it a potential latency reduction technique in Long Term Evolution. In this paper, we investigate resource scheduling in narrowband fourth generation Long Term Evolution networks through Network Simulator (NS3) simulations. The current release of NS3 does not include a semi-persistent scheduler for Long Term Evolution module. Therefore, we developed the semi-persistent scheduling feature in NS3 to evaluate and compare the performance in terms of uplink latency. We evaluate dynamic scheduling and semi-persistent scheduling in order to analyze the impact of resource scheduling methods on up-link latency.
The Datagram Transport Layer Security (DTLS) protocol has been designed to provide end-to-end security over unreliable communication links. Where its connection establishment is concerned, DTLS copes with potential loss of protocol messages by implementing its own loss detection and retransmission scheme. However, the default scheme turns out to be suboptimal for links with high transmission error rates and low data rates, such as wireless links in electromagnetically harsh industrial environments. Therefore, in this paper, as a first step we provide an analysis of the standard DTLS handshake's performance under such adverse transmission conditions. Our studies are based on simulations that model message loss as the result of bit transmission errors. We consider several handshake variants, including endpoint authentication via pre-shared keys or certificates. As a second step, we propose and evaluate modifications to the way message loss is dealt with during the handshake, making DTLS deployable in situations which are prohibitive for default DTLS.
The Transport Layer Security (TLS) protocol is a cornerstone of secure network communication, not only for online banking, e-commerce, and social media, but also for industrial communication and cyber-physical systems. Unfortunately, implementing TLS correctly is very challenging, as becomes evident by considering the high frequency of bugfixes filed for many TLS implementations. Given the high significance of TLS, advancing the quality of implementations is a sustained pursuit. We strive to support these efforts by presenting a novel, response-distribution guided fuzzing algorithm for differential testing of black-box TLS implementations. Our algorithm generates highly diverse and mostly-valid TLS stimulation messages, which evoke more behavioral discrepancies in TLS server implementations than other algorithms. We evaluate our algorithm using 37 different TLS implementations and discuss―by means of a case study―how the resulting data allows to assess and improve not only implementations of TLS but also to identify underspecified corner cases. We introduce suspiciousness as a per-implementation metric of anomalous implementation behavior and find that more recent or bug-fixed implementations tend to have a lower suspiciousness score. Our contribution is complementary to existing tools and approaches in the area, and can help reveal implementation flaws and avoid regression. While being presented for TLS, we expect our algorithm's guidance scheme to be applicable and useful also in other contexts. Source code and data is made available for fellow researchers in order to stimulate discussions and invite others to benefit from and advance our work.
The paper describes the methodology and experimental results for revealing similarities in thermal dependencies of biases of accelerometers and gyroscopes from 250 inertial MEMS chips (MPU-9250). Temperature profiles were measured on an experimental setup with a Peltier element for temperature control. Classification of temperature curves was carried out with machine learning approach.
A perfect sensor should not have thermal dependency at all. Thus, only sensors inside the clusters with smaller dependency (smaller total temperature slopes) might be pre-selected for production of high accuracy inertial navigation modules. It was found that no unified thermal profile (“family” curve) exists for all sensors in a production batch. However, obviously, sensors might be grouped according to their parameters. Therefore, the temperature compensation profiles might be regressed for each group. 12 slope coefficients on 5 degrees temperature intervals from 0°C to +60°C were used as the features for the k-means++ clustering algorithm.
The minimum number of clusters for all sensors to be well separated from each other by bias thermal profiles in our case is 6. It was found by applying the elbow method. For each cluster a regression curve can be obtained.
Recently, the demand for scalable, efficient and accurate Indoor Positioning Systems (IPS) has seen a rising trend due to their utility in providing Location Based Services (LBS). Visible Light Communication (VLC) based IPS designs, VLC-IPS, leverage Light Emitting Diodes (LEDs) in indoor environments for localization. Among VLC-based designs, Time Difference of Arrival (TDOA) based techniques are shown to provide very low errors in the relative position of receivers. Our considered system consists of five LEDs that act as transmitters and a single receiver (photodiode or image sensor in smart phone) whose position coordinates in an indoor environment are to be determined. As a performance criterion, Cramer Rao Lower Bound (CRLB) is derived for range estimations and the impact of various factors, such as, LED transmission frequency, position of reference LED light, and the number of LED lights, on localization accuracy has been studied. Simulation results show that depending on the optimal values of these factors, location estimation on the order of few centimeters can be realistically achieved.
Real-Time Ethernet has become the major communication technology for modern automation and industrial control systems. On the one hand, this trend increases the need for an automation-friendly security solution, as such networks can no longer be considered sufficiently isolated. On the other hand, it shows that, despite diverging requirements, the domain of Operational Technology (OT) can derive advantage from high-volume technology of the Information Technology (IT) domain. Based on these two sides of the same coin, we study the challenges and prospects of approaches to communication security in real-time Ethernet automation systems. In order to capitalize the expertise aggregated in decades of research and development, we put a special focus on the reuse of well-established security technology from the IT domain. We argue that enhancing such technology to become automation-friendly is likely to result in more robust and secure designs than greenfield designs. Because of its widespread deployment and the (to this date) nonexistence of a consistent security architecture, we use PROFINET as a showcase of our considerations. Security requirements for this technology are defined and different well-known solutions are examined according their suitability for PROFINET. Based on these findings, we elaborate the necessary adaptions for the deployment on PROFINET.
Solar irradiance prediction is vital for the power management and the cost reduction when integrating solar energy. The study is towards a ground image based solar irradiance prediction which is highly dependent on the cloud coverage. The sky images are collected by using ground based sky imager (fisheye lens). In this work, different algorithms for cloud detection being a preparation step for their segmentation are compared.
The fisheye camera has been widely studied in the field of ground based sky imagery and robot vision since it can capture a wide view of the scene at one time. However, serious image distortion is a major drawback hindering its wider use. To remedy this, this paperproposes a lens calibration and distortion correction method for detecting clouds and forecasting solar radiation. Finally, the radial distortion of the fisheye image can be corrected by incorporating the estimated calibration parameters. Experimental results validate the effectiveness of the proposed method.
This paper deals with the detection and segmentation of clouds on high-dynamic-range (HDR) images of the sky as well as the calculation of the position of the sun at any time of the year. In order to predict the movement of clouds and the radiation of the sun for a short period of time, the clouds thickness and position have to be known as precisely as possible. Consequently, the segmentation algorithm has to provide satisfactory results regardless of different weather, illumination and climatic conditions. The principle of the segmentation is based on the classification of each pixel as a cloud or as a sky. This classification is usually based on threshold methods, since these are relatively fast to implement and show a low computational burden. In order to predict if and when the sun will be covered by clouds, the position of the sun on the images has to be determined. For this purpose, the zenith and azimuth angles of the sun are determined and converted into XY coordinates.
Printed Electronics (PE) is a promising technology that provides mechanical flexibility and low-cost fabrication. These features make PE the key enabler for emerging applications, such as smart sensors, wearables, and Internet of Things (IoTs). Since these applications need secure communication and/or authentication, it is vital to utilize security primitives for cryptographic key and identification. Physical Unclonable Functions (PUF) have been adopted widely to provide the secure keys. In this work, we present a weak PUF based on Electrolyte-gated FETs using inorganic inkjet printed electronics. A comprehensive analysis framework including Monte Carlo simulations based on real device measurements is developed to evaluate the proposed PE-PUF. Moreover, a multi-bit PE-PUF design is proposed to optimize area usage. The analysis results show that the PE-PUF has ideal uniqueness, good reliability, and can operates at low voltage which is critical for low-power PE applications. In addition, the proposed multi-bit PE-PUF reduces the area usage around 30%.
Printed electronics offers certain technological advantages over its silicon based counterparts, such as mechanical flexibility, low process temperatures, maskless and additive manufacturing process, leading to extremely low cost manufacturing. However, to be exploited in applications such as smart sensors, Internet of Things and wearables, it is essential that the printed devices operate at low supply voltages. Electrolyte gated field effect transistors (EGFETs) using solution-processed inorganic materials which are fully printed using inkjet printers at low temperatures are very promising candidates to provide such solutions. In this paper, we discuss the technology, process, modeling, fabrication, and design aspect of circuits based on EGFETs. We show how the measurements performed in the lab can accurately be modeled in order to be integrated in the design automation tool flow in the form of a Process Design Kit (PDK). We also review some of the remaining challenges in this technology and discuss our future directions to address them.
In public transportation, the motor pool often consists of various different vehicles bought over a duration of many years. Sometimes, they even differ within one batch bought at the same time. This poses a considerable challenge in the storage and allocation of spare parts, especially in the event of damage to a vehicle. Correctly assigning these parts before the vehicle reaches the workshop could significantly reduce both the downtime and, therefore, the actual costs for companies. In order to achieve this, the current software uses a simple probability calculation. To improve the performance, the data of specific companies was analysed, preprocessed and used with several modelling techniques to classify and, therefore, predict the spare parts to be used in the event of a faulty vehicle. We summarize our experience running through the steps of the Cross Industry Standard Process for Data Mining and compare the performance to the previously used probability. Gradient Boosting Trees turned out to be the best modeling technique for this special case.
This paper describes the use of the single-linkage hierarchical clustering method in outlier detection for manufactured metal work pieces. The main goal of the study is to group defects that occur 5 mm into a work piece from the edge, i.e., the border of the metal work piece. The goal is to remove defects outside the area of interest as outliers. According to the assumptions made for the performance criteria, the single-linkage method has achieved better results compared to other agglomeration methods.
Targeting complex fractionated atrial electrocardiograms by automated algorithms during ablation of persistent atrial fibrillation has produced conflicting outcomes in previous electrophysiological studies and catheter ablation of atrial fibrillation and ventricular tachycardia. The aim of the investigation was to evaluate atrial and ventricular high frequency fractionated electrical signals with signal averaging technique.
Methods: Signal averaging electrocardigraphy allows high resolution ECG technique to eliminate interference noise signals in the recorded ECG. The algorithm use automatic ECG trigger function for signal averaged transthoracic, transesophageal and intra-cardiac ECG signals with novel LabVIEW software.
Results: The analysis in the time domain evaluated fractionated atrial signals at the end of the signal averaged P-wave and fractionated ventricular signals at the end of the QRS complex. We evaluated atrial flutter in the time domain with two-to-one atrioventricular conduction, 212.0 ± 4.1 ms atrial cycle length, 426.0 ± 8.2 ms ventricular cycle length, 58.2 ± 1.8 ms P-wave duration, 119.6 ± 6.4 ms PQ duration, 103.0 ± 2.4 ms QRS duration and 296.4 ± 6.8 ms QT duration. The analysis in the frequency domain evaluated high frequency fractionated atrial signals during the P-wave and high frequency fractionated ventricular signals during QRS complex.
Conclusions: Spectral analysis of signal averaging electrocardiography with novel LabVIEW software can be utilized to evaluate atrial and ventricular conduction delays in patients with atrial fibrillation and ventricular tachycardia. Complex fractionated atrial and ventricular electrocardiograms may be useful parameters to evaluate electrical cardiac bradycardia and tachycardia signals in atrial fibrillation and ventricular tachycardia ablation.
Cardiac resynchronization therapy (CRT) with hemodynamic optimized biventricular pacing is an established therapy for heart failure patients with sinus rhythm, reduced left ventricular ejection fraction and wide QRS complex. The aim of the study was to evaluate electrical right and left cardiac atrioventricular delay and left atrial delay in CRT responder and non-responder with sinus rhythm.
Methods: Heart failure patients with New York Heart Association class 3.0 ± 0.3, sinus rhythm and 27.7 ± 6.1% left ventricular ejection fraction were measured by surface ECG and transesophageal bipolar left atrial and left ventricular ECG before implantation of CRT devices. Electrical right cardiac atrioventricular delay was measured between onset of P wave and onset of QRS complex in the surface ECG, left cardiac atrioventricular delay between onset of left atrial signal and onset of left ventricular signal in the transesophageal ECG and left atrial delay between onset and offset of left atrial signal in the transesophageal ECG.
Results: Electrical atrioventricular and left atrial delay were 196.9 ± 38.7 ms right and 194.5 ± 44.9 ms left cardiac atrioventricular delay, and 47.7 ± 13.9 ms left atrial delay. There were positive correlation between right and left cardiac atrioventricular delay (r = 0.803 P < 0.001) and negative correlation between left atrial delay and left ventricular ejection fraction (r = −0.694 P = 0.026) with 67% CRT responder.
Conclusions: Transesophageal electrical left cardiac atrioventricular delay and left atrial delay may be useful preoperative atrial desynchronization parameters to improve CRT optimization.
Hintergrund: Richtung und Stärke des elektrischen Feldes (E-Feld) der biventrikulären (BV) Stimulation und elektrische interventrikuläre Desynchronisation sind bei Patienten mit Herzinsuffizienz und verbreitertem QRS Komplex von Bedeutung für den Erfolg der kardialen Resynchronisationstherapie (CRT). Das 3D Herzrhythmusmodell (HRM) ermöglicht die
Simulation von CRT und Hochfrequenz (HF) Ablation. Das Ziel der Studie besteht in der Integration von Schrittmacher- und Ablationselektroden in das HRM zur E-Feld Simulation der BV Stimulation und thermischen Feld (T-Feld) Simulation der HF Ablation von Vorhofflimmern (AF).
Methoden: Es wurden fünf multipolare linksventrikuläre (LV) Elektroden, eine epikardiale LV Elektrode, vier bipolare rechtsatriale (RA) Elektroden, zwei rechtsventrikuläre (RV) Elektroden und ein HF Ablationskatheter mit CST (Computer Simulation Technology, Darmstadt) modelliert und das HRM (Schalk et al: Clin Res Cardiol 106, Suppl 1, April 2017, P1812) um den Koronarvenensinus (CS) erweitert (HRM-CS). E-Feld Simulationen bei vorhofsynchroner BV Stimulation und bei RA Stimulation mit RV und LV Ableitung erfolgten mit den Elektroden Select Secure 3830, Capsure VDD-2 5038 und Attain OTW 4194 im HRM+CS (Fig.). F-Feld Simulationen der HF Ablation von AF bei CRT wurden mit integriertem Ablationskatheter AlCath G FullCircle (Biotronik) simuliert.
Ergebnisse: HRM-CS ermöglichte 3D E-Feld Simulationen bei vorhofsynchroner bipolarer BV Stimulation und bei bipolarer RA Stimulation mit bipolarer RV und LV Ableitung. RV und LV Stimulation erfolgten zeitgleich bei einer Amplitude von 3 V an der LV Elektrode und 1 V an der RV Elektrode mit einer Impulsbreite von jeweils 0,5 ms. Die von der BV Stimulationen erzeugten Fernpotentiale konnten von der RA Elektrode wahrgenommen werden. Das Fernpotential an der RA Elektrodenspitze betrug 32,86 mV und in 1 mm Abstand von der RA Elektrodenspitze ergab sich ein Fernpotential von 185,97 mV. HRM-CS ermöglichte 3D T-Feld Simulationen der HF Ablation von AF bei CRT. Das T-Feld bei HF Ablation des AV-Knotens wurde mit einer anliegenden Leistung von 5 W bei 420 kHz an der distalen 8 mm Ablationselektrode simuliert. Die Temperatur an der Katheterspitze betrug nach 5 s Ablationsdauer 88,66 °C, in 1 mm Abstand von der Katheterspitze im Myokard 42,17 °C und in 2 mm Abstand 37,49 °C.
Schlussfolgerungen: HRM-CS und Elektrodenmodelle ermöglichen die 3D Simulationen von E-Feldern bei vorhofsynchroner BV Stimulation, RA Stimulation mit RV und LV Wahrnehmung und von T-Feldern bei HF Ablation. E-Feld Simulationen von RA, RV und LV Stimulation und Sensing können möglicherweise zur Vorhersage von CRT Respondern genutzt werden.
In einer Vorlesung nicht abgehängt zu werden und die vielen Ergebnisse strukturiert zu sichern, ist für Studienanfänger eine große Herausforderung. Mitschriebe sind sehr oft unvollständig, unstrukturiert oder „zerfläddert“. Mitschreib-Marathon und Mitdenken schließen sich bei vielen aus. Auch aktivierende Lehrmethoden, Medienwechsel, Lehrvideos führen oft dazu, dass eine strukturierte Sicherung der Inhalte des Lehrgesprächs noch erschwert wird.
Es wird ein Best Practice Beispiel gezeigt, Mathematik-Vorlesungen über ein Tablet-basiertes Mitmach-Skript zu gestalten. Dieses dient als Schrittmacher zwischen Input- und Verarbeitungsphasen und unterstützt die strukturierte Verschriftlichung, indem es Vorteile von Tafel, PPT und klassischem Skript vereint. Traditionelle Methoden werden mit technologischen Möglichkeiten kombiniert, um die angesprochenen Herausforderungen bewusster im Lehrstil zu berücksichtigen. Verbindungen zu Virtual Classroom und Video-gestützter Lehre werden aufgezeigt.
Wireless sensor networks have recently found their way into a wide range of applications among which environmental monitoring system has attracted increasing interests of researchers. Such monitoring applications, in general, don way into a wide range of applications among which environmental monitoring system has attracted increasing interests of researc latency requirements regarding to the energy efficiency. Also a challenge of this application is the network topology as the application should be able to be deployed in very large scale. Nevertheless low power consumption of the devices making up the network must be on focus in order to maximize the lifetime of the whole system. These devices are usually battery-powered and spend most of their energy budget on radio transceiver module. A so-called Wake-On-Radio (WoR) technology can be used to achieve a reasonable balance among power consumption, range, complexity and response time. In this paper, some designs for integration of WOR into IEEE 802.1.5.4 are to be discussed, providing an overview of trade-offs in energy consumption while deploying the WoR schemes in a monitoring system.
Environmental Monitoring is an attractive application field for Wireless Sensor Network (WSN). Water Level Monitoring helps to increase the efficiency of water distribution and management. In Pakistan, the world’s largest irrigation system covers 90.000 km of channels which needs to be monitored and managed on different levels. Especially the sensor systems for the small distribution channels need to be low energy and low cost. The distribution presents a technical solution for a communication system which is developed in a research project being co-funded by German Academic Exchange Service (DAAD). The communication module is based on IEEE-802.15.4 transceivers which are enhanced through Wake-On-Radio (WOR) to combine low-energy and real-time behavior. On higher layers, IPv6 (6LoWPAN) and corresponding routing protocols like Routing Protocol for Low power and Lossy Networks (RPL) can extend range of the network. The data are stored in a database and can be viewed online via a web interface. Of course, also automatic data analysis can be performed.
We report the use of the Raman spectral information of the chemical compound toluene C7H8 as a reference on the analysis of laboratory-prepared and commercially acquired gasoline-ethanol blends. The rate behavior of the characteristic Raman lines of toluene and gasoline has enabled the approximated quantification of this additive in commercial gasoline-ethanol mixtures. This rate behavior has been obtained from the Raman spectra of gasoline-ethanol blends with different proportions of toluene.
All these Raman spectra have been collected by using a self-designed, frequency precise and low-cost Fourier-transform Raman spectrometer (FT-Raman spectrometer) prototype. This FT-Raman prototype has helped to accurately confirm the frequency position of the main characteristic Raman lines of toluene present on the different gasoline-ethanol samples analyzed at smaller proportions than those commonly found in commercial gasoline-ethanol blends. The frequency accuracy validation has been performed by analyzing the same set of toluene samples with two additional state-of-the-art commercial FT-Raman devices. Additionally, the spectral information has been contrasted, with highly-correlated coefficients as a result, with the values of the standard Raman spectrum of toluene.
The application of leaky feeder (radiating) cables is a common solution for the implementation of reliable radio communication in huge industrial buildings, tunnels and mining environment. This paper explores the possibilities of leaky feeders for 1D and 2D localization in wireless systems based on time of flight chirp spread spectrum technologies. The main focus of this paper is to present and analyse the results of time of flight and received signal strength measurements with leaky feeders in indoor and outdoor conditions. The authors carried out experiments to compare ranging accuracy and radio coverage area for a point-like monopole antenna and for a leaky feeder acting as a distributed antenna. In all experiments RealTrac equipment based on nanoLOC radio standard was used. The estimation of the most probable path of a chirp signal going through a leaky feeder was calculated using the ray tracing approach. The typical non-line-of-sight errors profiles are presented. The results show the possibility to use radiating cables in real time location technologies based on time-of-flight method.
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 and its benefit for traffic safety applications is evaluated. 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. The Ko-TAG proposal enriches the current IEEE802.11p real-time characteristics needed for precise time-of-flight real-time localization. This contribution describes the development of a subsystem, which extends the functionality of IEEE802.11p and 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. The next step will be field measurements to verify the simulation results.
Transcatheter aortiv valve implantation is a new safe strategy treatment for patients with symptomatic severe aortic stenosis and high operative risk. The aim of the study was to compare the pre-and post- muiscatheter aortiv valve implantation procedures to determine the atrioventricuktr conduction time as a potential predictor of permanent pacemaker therapy requirement after transcatheter aortiv valve implantation. The transcatheter aortiv valve implantation patients were divided into groups without pacemaker and with dual or single chamber pacemEtker with diffent atrioventrieular conduction time disturbance before and after transcatheter aortiv valve implantation. In heart failure, patients without permanent pacemaker therapy after transcatheter aortiv valve implantation, atrioventricular conduction time was prolonged after transcatheter aortiv valve implantation. In patients with permanent dual chamber pacemaker therapy after transcatheter aortiv valve implantation, atrioventricular conduction time was normalised with dual chaniber atrioventrieuku pacing mode. Atrioventricular conduction time may be a useful parameter to evaluate the risk of post-procedural atrioventricular conduction block and permanent pacemaker therapy in transcatheter north, valve implantation patients.
Die Geschäftsleitung und Führungskräfte von Eller Repro+Druck beschlossen im Juli 1994 die Teilnahme am damls noch neuen EU-Öko-Audit. Die Durchführung des Audits ist für 1996 geplant. Zwei Diplomanden der FH Offenburg wurde die Möglichkeit gegeben, als externe Berater für Eller Repro+Druck ihre Diplomarbeit über die Vorbereitung zum Öko-Audit zu schreiben. Der Betrieb (170 Mitarbeiter) verfügt über elektronische Bildverarbeitung auf Scitex- und Mac-Schiene, derzeit noch konventionelle Plattenkopie und -entwicklung, fünf Offsetrotationen sowie Weiterverarbeitung mit Sammelheftern und Falzmaschinen. Der Referent berichtet über die Erfahrungen, die sein Unternehmen bis zum Herbst 1995 mit der Vorbereitung zum Öko-Audit gemacht hat, und gibt Praxistips. Zusammen mit den Beratern wurden eine Aufnahme der betrieblichen Situation durchgeführt, Maßnahmen geplant und zum Teil durchgeführt.
In der Wertanalyse ist die Methodik TRIZ (Theorie der Lösung erfinderischer Problemstellungen) seit vielen Jahren als Werkzeug zur Kostensenkung oder zur Steigerung der Funktionalität von Produkten bekannt. Seit ihrem ersten Bekanntwerden in Westeuropa hat sich auch TRIZ weiterentwickelt. So wurden Methoden zur Modellierung von Systemen inzwischen erweitert und um Werkzeuge zur schnellen Lösungsfindung, zur Fehlervoraussage und zur Produktplanung neu entwickelt. Durch den weltweiten wissenschaftlichen Fortschritt, die Verwendung unterschiedlicher Sprachen und neue Literatur ist andererseits auch die verwendete Terminologie angewachsen und nicht mehr eindeutig. Die neue VDI-Richtlinie 4521, von deren erstem Teil nun der Gründruck vorliegt, zielt deswegen auf eine Standardisierung der Terminologie und eine vereinheitlichte Beschreibung der Methoden ab. Mit ihrer Hilfe sollen das Studium der Methodik erleichtert, die Benutzung von Literatur vereinfacht und Inhalte der TRIZ klarer darstellbar werden.
The communication between objects, i.e. between cars (car-2-car, C2C), between cars and infrastructure (car-2-infrastructure, C2I) and between cars and vulnerable road users (car-2-VRU, C2VRU) is a major stepping stone towards traffic applications to enable efficient and safe traffic flow. However, these applications pose very high requirements to the communication protocols, which go beyond the capabilities of an available standardized solution.
This contribution shows how iterative design processes can help to fulfill these requirements, while re-using a maximum of elements from one level to the next and thus avoiding unrealistic overhead. In especially, the added value of simulation and emulation in this iterative process is elaborated.
The formation of secondary phases in the porous electrodes is a severe mechanism affecting the lifetime of solid oxide fuel cells (SOFC). It can occur via various chemical mechanisms and it has a significant influence on cell performance due to pore clogging and deactivation of active surfaces and triple-phase boundary (TPB). We present a modeling and simulation study of nickel oxide formation (reoxidation) and carbon formation (coking) within the SOFC anode. We use a 2D continuum model based on a multi-phase framework [Neidhardt et al., J. Electrochem. Soc., 159, 9 (2012)] that allows the introduction of arbitrary solid phases (here: Ni, YSZ, NiO, Carbon) plus gas phase. Reactions between the bulk phases are modeled via interface-adsorbed species and are described by an elementary kinetic approach. Published experimental data are used for parameterization and validation. Simulations allow the prediction of cell performance under critical operation conditions, like (i) a non-fuel operation test, where NiO formation is taking place (Figure 1a), or (ii) an open circuit voltage (OCV) stability test under hydrocarbon atmosphere, where solid carbon is formed (Figure 1b). Results are applied for enhanced interpretation of experimental data and for prediction of safe operation conditions.
6LoWPAN (IPv6 over Low Power Wireless Personal Area Networks) is gaining more and more attraction for the seamless connectivity of embedded devices for the Internet of Things. It can be observed that most of the available solutions are following an open source approach, which significantly leads to a fast development of technologies and of markets. Although the currently available implementations are in a pretty good shape, all of them come with some significant drawbacks. It was therefore decided to start the development of an own implementation, which takes the advantages from the existing solutions, but tries to avoid the drawbacks. This paper discussed the reasoning behind this decision, describes the implementation and its characteristics, as well as the testing results. The given implementation is available as open-source project under [15].
Non-fluoroscopic Imaging with MRT/CT Image Integration - Catheter Positioning with Double Precision
(2014)
Introduction: When antiarrhythmic drug therapy has failed, different approaches of pulmonary vein isolation are considered a reasonable option in the treatment of atrial fibrillation. It will be performed predominantly by radiofrequency catheter ablation. As the individual anatomy of left atrium and the pulmonary veins differs considerably, accurate visualization of these structures is essential during catheter positioning. Using non-fluoroscopic electroanatomic mapping system with image integration, electroanatomic mapping can be combined with highly detailed anatomical MRT or CT information on complex left atrial structures. This may facilitate catheter navigation during ablation for atrial fibrillation.
Methods: The CARTO XP electroanatomic system was used in a project during biomedical engineering study to practice image integration of anonymized real patients that underwent pulmonary vein isolation by CARTO XP and a MRT/CT procedure. Using the image integration software, MRT or CT images were imported into the CARTO XP system. The next process was segmentation of the acquired images. It involves dividing the images into different regions in order to select the structures of interest. In clinical routine, this segmentation has to be performed before catheter ablation. Then, the segmented images were aligned with the reconstructed electroanatomic maps. This consists of several steps, including selection of the left atrium, scaling of the reconstructed geometry, fusion of the structures using landmarks, and optimization of the integration by adjusting the reconstructed geometry of the left atrium.
Results: In the 3 months lasting period of the project, image integration was trained in 13 patients undergoing catheter ablation for atrial fibrillation. Within this period, time consumption for the process decreased from about 90 minutes at the beginning to about 35 minutes at the end for one patient.
Conclusion: Image integration into non-fluoroscopic electroanatomic map is a sophisticated tool in cardiac radiofrequency catheter ablation. Intensive training is necessary to control the procedure.
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.
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.
Components of rocket engines as actively cooled combustion chambers must withstand high pressure as well as severe and complex thermal transients. While the thermal transients result in temperature gradients and, thus, in constraint thermal strains, the pressure load induces mean stresses. To assess the mechanical behaviour of such components during design via finite-element calculations, constitutive models are necessary that describe the time- and temperature-dependent plasticity of the material appropriately.
Advanced models account for viscoplastic deformations including isotropic and kinematic hardening, recovery and ratcheting. However, the models contain a relatively large number of temperature-dependent material properties that must be determined on the basis of data of material tests. The determination of the properties is a non-trivial task because it is not clear which loading history must be applied in the tests for a certain material to obtain stable and robust (i.e. objective) material properties. Consequently, the determined properties are depending on the underlying loading history in the tests as well as on the experience and valuation of the person that determined the properties. This results in uncertainties during the assessment of the components that must be faced with conservative designs leading to negative consequences in terms of mass and costs.
It is the aim of this work funded by the European Space Agency ESA to derive a procedure to determine stable and robust material properties of an advanced viscoplastic constitutive model for aerospace materials. To this end, a special loading history is applied in isothermal material tests conducted with copper at different temperatures in the temperature range from 300 to 700 K. To determine the material properties and to assess stability and robustness methods for numerical optimization as well as analytical and statistical methods are used. The determined material properties are validated on the basis of results of thermomechanical material tests also conducted in the temperature range from 300 to 700 K.
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.
Cardiac resynchronization therapy is an established therapy for heart failure patients with sinus rhythm, reduced left ventricular ejection fraction and prolongation of QRS duration. The aim of the study was to evaluate ventricular desynchronization with electrical interventricular delay (IVD) to left ventricular delay (LVD) ratio in atrial fibrillation heart failure patients. IVD and LVD were measured by transesophageal posterior left ventricular ECG recording. In atrial fibrillation heart failure patients with prolonged QRS duration, the mean IVD-to-LVD-ratio was 0.84 +/- 0.42 with a range from 0.17 to 2.2 IVD-to-LVD-ratio. IVD-to-LVD-ratio correlated with QRS duration. IVD-to-LVD-ratio may be a useful parameter to evaluate electrical ventricular desynchronization in atrial fibrillation heart failure patients.
Cardiac resynchronization therapy with atrioventricular and interventricular pacing delay optimized biventricular pacing is an established therapy for heart failure patients with sinus rhythm and reduced left ventricular ejection fraction. The aim of the study was to evaluate atrioventricular and interventricular pacing delay optimization in cardiac resynchroniza-tion therapy by transthoracic impedance cardiography in biventricular pacing with different left ventricular electrode po-sition. In biventricular pacing heart failure patients with lateral, posterolateral and anterolateral left ventricular electrode position, the mean optimal atrioventricular sening delay was 108.6 ± 20.3 ms and the mean optimal interventricular pac-ing delay -12.3 ± 25.9 ms. Transthoracic impedance cardiography may be a useful technique to optimize atrioventricular and interventricular pacing delay in biventricular pacing with different left ventricular electrode position.
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.
Distribution of esophageal interventricular conduction delays in CRT patients and healthy subjects
(2015)
6LoWPAN (IPv6 over Low Power Wireless Personal Area Networks) is gaining more and more attraction for the seamless connectivity of embedded devices for the Internet of Things (IoT). Whereas the lower layers (IEEE802.15.4 and 6LoWPAN) are already well defined and consolidated with regard to frame formats, header compression, routing protocols and commissioning procedures, there is still an abundant choice of possibilities on the application layer. Currently, various groups are working towards standardization of the application layer, i.e. the ETSI Technical Committee on M2M, the IP for Smart Objects (IPSO) Alliance, Lightweight M2M (LWM2M) protocol of the Open Mobile Alliance (OMA), and OneM2M. This multitude of approaches leaves the system developer with the agony of choice. This paper selects, presents and explains one of the promising solutions, discusses its strengths and weaknesses, and demonstrates its implementation.
This paper presents a practice and science orientated education approach for freshman students of interdisciplinary bachelor engineering degree programs. This approach is meant to enhance the motivation and success of freshman students during their whole study. The education approach is called Fit4PracSis (Fit for Practice and Sciences) It was started to develop, set up and establish an education approach, which is building a relationship to students' future profession and to scientific working during the introductory study phase. The freshman students will be trained early in important skills, which are necessary for achieving the final degree successfully and handling of future business and research activities.
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.
Both German and French Air-Source Heat Pump (ASHP) markets have been enjoying an overall upwards trend for many years but, nevertheless, they remain merely slightly penetrated. In terms of market players and their share, the French market is aptly diversified, whereas the German one, being utterly dominated by one single manufacturer, is badly in need of some diversification. At the same time Korean ASHP manufacturers are targeting the French but not German ASHP market. The main purpose of the paper is to find out likely reasons for their one-sided engagement, primarily those associated with the ASHP technology and its system-related aspects.
In online analytical processing (OLAP), filtering elements of a given dimensional attribute according to the value of a measure attribute is an essential operation, for example in top-k evaluation. Such filters can involve extremely large amounts of data to be processed, in particular when the filter condition includes “quantification” such as ANY or ALL, where large slices of an OLAP cube have to be computed and inspected. Due to the sparsity of OLAP cubes, the slices serving as input to the filter are usually sparse as well, presenting a challenge for GPU approaches which need to work with a limited amount of memory for holding intermediate results. Our CUDA solution involves a hashing scheme specifically designed for frequent and parallel updates, including several optimizations exploiting architectural features of Nvidia’s Fermi and Kepler GPUs.
Smoothie: a solution for device and content independent applications including 3D imaging as content
(2014)
Network landscape of recent time contains many different network technologies, a wide range of end-devices with a large scale of capabilities and power, and an immense quantity of information represented in different data formats. Research on 3D imaging, virtual reality and holographic techniques will result in new user interfaces (UI) for mobile devices and will increase their diversity and variety. A lot of effort is being made in order to establish open, scalable and seamless integration of various technologies and content presentation for different devices including those that are mobile, considering the individual situation of the end user. Till today the research is going on in different parts of the world but the task is not completed yet. The goal of this research work is to find a way to solve the above stated problems by investigating system architectures to provide unconstrained, continuous and personalized access to the content and interactive applications everywhere and at anytime with different devices. As a Solution of the problem considered, a new architecture named “Smoothie” is proposed.
Im Projekt bwLehrpool wurde ein verteiltes System für die flexible Nutzung von Rechnerpools durch Desktop-Virtualisierung entwickelt. Auf Basis eines zentral gebooteten Linux- Grundsystems können beliebige virtualisierbare Betriebssysteme für Lehrund Prüfungszwecke zentral bereitgestellt und lokal auf den Maschinen aus-gewählt werden. Die verschiedenen Ar- beitsumgebungen müssen nicht mehr auf den PCs installiert werden und erlauben so eine multifunktionale Nutzung von PCs und Räumen für vielfältige Lehrund Lernszenarien sowie für elektronische Prüfungen. bwLehrpool abstrahiert von der PC-Hardware vor Ort und ermöglicht den Dozenten die eigene Gestaltung und Verwaltung ihrer Softwareumgebungen als Self-Service. Darüber hinaus fördert bwLehrpool den hochschulübergreifenden Austausch von Kursumgebungen.
Flexible Three-dimensional Camera-based Reconstruction and Calibration of Tracked Instruments
(2016)
Navigated instruments commonly include applied parts, e.g. burrs or saw blades, that need to be calibrated with respect to the attached or integrated tracker. Since this calibration has to be very precise, it is often performed by the manufacturer. However, due to the great variety of instruments and the option to exchange the applied parts (e.g. burrs) there is a definite demand for flexible and generic calibration techniques. Furthermore, if we look into the medical field, there is also a need for calibrating sterile instruments. We propose a new and flexible camera-based calibration technique that addresses these demands by working contactlessly, precisely, and generically for a large variety of tracked instruments. This is realized using one or more tracked cameras which are calibrated with respect to an attached or integrated tracker. The tracked instrument is rotated in front of the camera(s) and its 3D geometry and surface are reconstructed from the 2D images in the coordinate system of the attached or integrated tracker. The 3D geometry of the navigated instrument was reconstructed with an accuracy of under 0.2 mm. The radius of a sphere-shaped instrument was reconstructed with an RMS deviation of 0.015mm.
Wireless sensor networks have found their way into a wide range of applications among which environmental monitoring systems have attracted increasing interests of researchers. The main challenges for the applications are scalability of the network size and energy efficiency of the spatially distributed motes. These devices are mostly battery-powered and spend most of their energy budget on the radio transceiver module. A so-called Wake-On-Radio (WOR) technology can be used to achieve a reasonable balance among power consumption, range, complexity and response time. In this paper, a novel design for integration of WOR into IEEE802.1.5.4 is presented, which flexibly allows trade-offs in energy consumption between sender and receiver station, between real-time capability and energy consumption. For identical behavior, the proposed scheme is significantly more efficient than other schemes, which were proposed in recent publications, while preserving backward compatibility with standard IEEE802.15.4 transceivers.
Ultra wide band (UWB) signals are well suited both for short-range wireless communication and for high-precision localization applications. Channel impulse response (CIR) analysis in UWB systems is a major element in localization estimation. In this paper, practical aspects of CIR are presented. I.e. a technique for the construction of the accumulated echo-gram of a multipath delayed signal is proposed. Decawave hardware was used to demonstrate the technique of analysis of fine structure of signals with a sub-nanosecond resolution. Temporal stability, reliability and two-way characteristics of such echo-grams are discussed as well. The results of using two EVK1000 radio modules as a radar installation to detect a target in indoor environments prove that a low cost UWB intrusion detection and through-the-wall-vision systems might be developed using the proposed technique.
In the work at hand, we combine a Private Information Retrieval (PIR) protocol with Somewhat Homomorphic Encryption (SHE) and use Searchable Encryption (SE) with the objective to provide security and confidentiality features for a third party cloud security audit. During the auditing process, a third party auditor will act on behalf of a cloud service user to validate the security requirements performed by a cloud service provider. Our concrete contribution consists of developing a PIR protocol which is proceeding directly on a log database of encrypted data and allowing to retrieve a sum or a product of multiple encrypted elements. Subsequently, we concretely apply our new form of PIR protocol to a cloud audit use case where searchable encryption is employed to allow additional confidentiality requirements to the privacy of the user. Exemplarily we are considering and evaluating an audit of client accesses to a controlled resource provided by a cloud service provider.
Agile Business Intelligence als Beispiel für ein domänenspezifisch angepasstes Vorgehensmodell
(2016)
Business-Intelligence-Systeme stellen durch ihre Unterstützung bei der Entscheidungsfindung für Unternehmen eine wichtige Rolle dar. Mit einer stetig dynamischeren Unternehmensumwelt geht daher die Anforderung nach der agilen Entwicklung dieser Systeme einher, so dass in der BI-Domäne zunehmend erfolgreich agile Methoden und Vorgehensmodelle eingesetzt werden. Die Weiterentwicklung und Anpassung von BI-Systemen ist dahingehend besonders, dass diese in der Regel langjährig gewachsenen Systemen und Strukturen betreffen, die strengen regulatorischen Rahmenbedingungen unterliegen, was eine Herausforderung für agile Vorgehensweisen darstellt. Wurden die Werte und Prinzipien des agilen Manifests [AM01] und die daraus abgeleiteten Methoden zu Beginn meist eins zu eins auf den Bereich BI übertragen, so hat sich das Verständnis von BI- Agilität als ganzheitliche Eigenschaft der BI im deutschsprachigen Raum etabliert, und agile Me- thoden wurden auf die Besonderheiten der BI-Domäne adaptiert. In diesem Beitrag werden BI-Agilität und Agile BI erläutert, ein Ordnungsrahmen für Maßnahmen zur Steigerung der BI-Agilität eingeführt sowie Herausforderungen bei Agile BI erläutert.
Die Verwendung von Kameras als Messmittel für medizinische Anwendungen setzt deren präzise Kalibrierung voraus. Gängige Verfahren modellieren die Abbildungseigenschaften einer Kamera mittels perspektivischer Projektion und parametrisierter Funktionen zur Beschreibung von Linsenverzerrung. In den Randbereichen des Kamerabildes sind diese Modelle oft unzureichend. Außerdem bedingt die Verwendung starrer Kalibriermuster eine in der Regel kleine Anzahl an nicht gleichmäßig verteilten Punktkorrespondenzen zur Bestimmung der Modellparameter. In der vorliegenden Arbeit wird ein vollkommen neues und nicht auf Modellen basierendes Kalibrierverfahren vorgestellt, bei dem jedes Kamerapixel unabhängig von jedem anderen kalibriert wird.