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In previous work we [1] and other authors (e.g. [2]) have shown that agent-based systems are successful in optimizing delivery plans of single logistics companies and are meanwhile successfully productive in industry. In this paper we show that agent-based systems are particularly useful to also optimize transport across logistics companies. In intercompany optimization, privacy is of major importance between the otherwise competing companies. Some data has to be treated strictly private like the cost model or the constraint model. Other data like order information has to be shared. However, typically the amount of orders released to other companies has also to be limited. We show that our agent-based approach can be easily fine tuned to trade off privacy against the benefit of cooperation.
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)
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 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.
A simple measuring method for acquiring the radiation pattern of an ultrawide band Vivaldi antenna is presented. The measuring is performed by combining two identical Vivaldi antennas and some of the intrinsic properties of a stepped-frequency continue wave radar (SFCW radar) in the
range from 1.0 GHz to 6.0 GHz. A stepper-motor provided the azimuthal rotation for one of the antennas from 0 ◦ to 360 ◦. The tests have been performed within the conventional environment (laboratory / office) without using an anechoic chamber or absorbing materials. Special measuring devices have not been used either. This method has been tested with different pairs of Vivaldi antennas and it can be also used for different ones (with little or no change in the system), as long as their operational
bandwidth is within the frequency range of the SFCW radar.
Keywords — SFCW Radar, Antenna Gain Characterization,
Azimuthal Radiation Pattern
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.
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.
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.
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.
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.
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.
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.
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.
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].
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.
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.
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.
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.
This work describes a non-parametric camera-based method for the calibration of Optical See-Through Glasses (OSTG). Existing works model the optical system through perspective projection and parametric functions. In the border areas of the displays such models are often inadequate. Moreover, rigid calibration patterns, that produce only a small amount of non-equidistant point correspondences, are used. In order to overcome these disadvantages every single display pixel is calibrated individually. The error prone user interaction is avoided by using cameras placed behind the displays of the OSTG. The displays show a shifting pattern that is used to calculate the pixels' locations. A camera mounted rigidly on the OSTG is used to find the relations between the system components. The obtained results show better accuracies than in previous works and prove that a second calibration step for user adaptation is necessary for high accuracy applications.
Die Vielfalt der Protokolle, die praktisch auf allen Ebenen der Netzwerkkommunikation zu berücksichtigen ist, stellt eine der großen Herausforderungen bei der fortschreitenden Automatisierung des intelligenten Hauses dar. Unter dem Überbegriff Internet der Dinge (Internet of Things) entstehen gegenwärtig zahlreiche neue Entwicklungen, Standards, Allianzen und so genannte Ökosysteme. Diese haben die Absicht einer horizontalen Integration gewerkeübergreifender Anwendungen und verfolgen fast alle das Ziel, die Situation zu vereinfachen, die Entwicklungen zu beschleunigen und Markterfolge zu erreichen. Leider macht diese Vielfalt momentan die Welt aber eher noch komplexer und bringt damit das Risiko mit sich, genau das Gegenteil der ursprünglichen Absichten zu erreichen. Dieser Beitrag versucht, die Entwicklungen möglichst systematisch zu kategorisieren und mögliche Lösungsansätze zu beschreiben.
Signal detection and bandwidth estimation, also known as channel segmentation or information channel estimation, is a perpetual topic in communication systems. In the field of radio monitoring this issue is extremely challenging, since unforeseeable effects like fading occur accidentally. In addition, most radio monitoring devices normally scan a wide frequency range of several hundred MHz and have to detect a multitude of different signals, varying in signal power, bandwidth and spectral shape. Since narrowband sensing techniques cannot be directly applied, most radio monitoring devices use Nyquist wideband sensing to discover the huge frequency range. In practice, sensing is normally conducted by an FFT sweep spectrum analyzer that delivers the power spectral density (PSD) values to the radio monitoring system. The channel segmentation is the initial step of a comprehensive signal analysis in a radio monitoring system based on the PSD values. In this paper, a novel approach for channel segmentation is presented that is based on a quantization and a histogram evaluation of the measured PSD. It will be shown that only the combination of both evaluations will lead to an successful automatic channel segmentation. The performance of the proposed algorithm is shown in a real radio monitoring szenario.
The industry of the agave-derived bacanora, in the northern Mexican state of Sonora, has been growing substantially in recent years. However, this higher demand still lies under the influences of a variety of social, legal, cultural, ecological and economic elements. The governmental institutions of the state have tried to encourage a sustainable development and certain levels of standardization in the production of bacanora by applying different economical and legal strategies. However, a large portion of this alcoholic beverage is still produced in a traditional and rudimentary fashion. Beyond the quality of the beverage, the lack of proper control, by using adequate instrumental methods, might represent a health risk, as in several cases traditional-distilled beverages can contain elevated levels of harmful materials. The present article describes the qualitative spectral analysis of samples of the traditional-produced distilled beverage bacanora in the range from 0 cm−1 to 3500 cm−1 by using a Fourier Transform Raman spectrometer. This particular technique has not been previously explored for the analysis of bacanora, as in the case of other beverages, including tequila. The proposed instrumental arrangement for the spectral analysis has been built by combining conventional hardware parts (Michelson interferometer, photo-diodes, visible laser, etc.) and a set of self-developed evaluation algorithms. The resulting spectral information has been compared to those of pure samples of ethanol and to the spectra from different samples of the alcoholic beverage tequila. The proposed instrumental arrangement can be used the analysis of bacanora.
The Bluetooth community is in the process to develop mesh technology. This is highly promising as Bluetooth is widely available in Smart Phones and Tablet PCs, allowing an easy access to the Internet of Things. In this paper work, we investigate the performance of Bluetooth enabled mesh networking that we performed to identify the strengths and weaknesses. A demonstrator for this protocol has been implemented by using the Fruity Mesh protocol implementation. Extensive test cases have been executed to measure the performance, the reliability, the power consumption and the delay. For this, an Automated Physical Testbed (APTB), which emulates the physical channels has been used. The results of these measurements are considered useful for the real implementation of Bluetooth; not only for home and building automation, but also for industrial automation.
Due to a controversial enrollment policy in most engineering programs at German Universities of Applied Sciences (UAS), many freshmen show very low school grades in key subjects like Math and Physics. Nevertheless they expect to be entertained in the lectures and get demotivated easily. Despite initial reservations, a cheer-and-challenge approach was developed for teaching Mechanics to freshmen having very diverse school grades. When tested, it showed astonishing results.
IPv6 over LoRaWAN™
(2016)
Although short-range wireless communication explicitly targets local and regional applications, range continues to be a highly important issue. The range directly depends on the so-called link budget, which can be increased by the choice of modulation and coding schemes. The recent transceiver generation in particular comes with extensive and flexible support for software-defined radio (SDR). The SX127× family from Semtech Corp. is a member of this device class and promises significant benefits for range, robust performance, and battery lifetime compared to competing technologies. This contribution gives a short overview of the technologies to support Long Range (LoRa™) and the corresponding Layer 2 protocol (LoRaWAN™). It particularly describes the possibility to combine the Internet Protocol, i.e. IPv6, into LoRaWAN™, so that it can be directly integrated into a full-fledged Internet of Things (IoT). The proposed solution, which we name 6LoRaWAN, has been implemented and tested; results of the experiments are also shown in this paper.
Battery degradation is a complex physicochemical process that strongly depends on operating conditions and environment. We present a model-based analysis of lithium-ion battery degradation in smart microgrids, in particular, a single-family house and an office tract with photovoltaics generator. We use a multi-scale multi-physics model of a graphite/lithium iron phosphate (LiFePO4, LFP) cell including SEI formation as ageing mechanism. The cell-level model is dynamically coupled to a system-level model consisting of photovoltaics, inverter, power consumption profiles, grid interaction, and energy management system, fed with historic weather data. The behavior of the cell in terms of degradation propensity, performance, state of charge and other internal states is predicted over an annual operation cycle. As result, we have identified a peak in degradation rate during the battery charging process, caused by charging overpotentials. Ageing strongly depends on the load situation, where the predicted annual capacity fade is 1.9 % for the single-family house and only 1.3 % for the office tract.
With increasing flexible AC transmission system (FACTS) devices in operation, like the most versatile unified power flow controller (UPFC), the AC/DC transmission flexibility and power system stability have been suffering unprecedented challenge. This paper introduces the user-defined modeling (UDM) method into the UPFC dynamic modeling process, to deal with the challenging requirements of power system operation. This has also been verified using a leading-edge stability analysis software named DSATools TM in the IEEE-39 bus benchmark system. The characteristics of steady-state and dynamic responses are compared and analyzed under different conditions. Furthermore, simulation results prove the feasibility and effectiveness of the proposed UPFC in terms of both the independent regulation of power flow and the improvement of transient stability.
Background: Cardiac resynchronization therapy (CRT) is an established therapy for heart failure (HF) patients (P) with reduced left ventricular (LV) ejection fraction and electrical interventricular desynchronization, but not all P improved clinically. The aim of the study was to evaluate electrical interventricular delay (IVD) to LV delay (LVD) ratio in atrial fibrillation (AF) CRT responder (R) and non-responder (NR).
Methods: AF P (n = 18, age 60.6 ± 11.4 years, 1 female, 17 males) with HF New York Heart Association (NYHA) class 3.0 ± 0.2, 25.3 ± 5.9 % LV ejection fraction and 157.8 ± 24.4 ms QRS duration (QRSD) were measured by surface ECG and focused transesophageal bipolar LV ECG before implantation of CRT pacemaker (n = 2) or CRT defibrillator (n = 16). IVD was measured between onset of QRS in the surface ECG and onset of LV signal in the LV ECG. LVD was measured between onset and offset of LV signal in the LV ECG.
Results: Electrical ventricular desynchronization in AF CRT P were 61.9 ± 26.9ms IVD, 80.6 ± 24.3ms LVD, 0.85 ± 0.41 IVD-LVD-ratio (Figure), 3.12 ± 1.89 QRSD-IVD-ratio and 2.07 ± 0.47 QRSD-LVD-ratio. There were 72.2 % AF CRT R (n = 13) with 64.2 ± 24.6ms IVD and 77.8 ± 21.6ms LVD with Pearson correlation to 0.89 ± 0.39 IVD-LVD-ratio (r = 0.87, P < 0.01; r = -0.69, P < 0.01), 2.82 ± 1.32 QRSD-IVD-ratio (r = -0.76, P < 0.01; r = 0.67, P = 0.011) and 2.13 ± 0.46 QRSD-LVD-ratio (r = 0.57, P = 0.041; r = -0.85, P < 0.01). There were 27.8% AF CRT NR (n = 5) with 56.0 ± 34.5ms IVD and 87.8 ± 31.9ms LVD without correlation to 0.74 ± 0.48 IVD-LVD-ratio, 3.88 ± 2.98 QRSD-IVD-ratio and 1.90 ± 0.48 QRSD-LVD-ratio. During 15.3 ± 13.1 month CRT follow-up, the AF CRT R NYHA class improved from 3.0 ± 0.2 to 2.2 ± 0.3 (P < 0.001). During 18.8 ± 20.7 month CRT follow-up, the AF CRT NR NYHA class not improved from 3 to 3.3 ± 0.97.
In this paper we present the implementation of a model-predictive controller (MPC) for real-time control of a cable-robot-based motion simulator. The controller computes control inputs such that a desired acceleration and angular velocity at a defined point in simulator’s cabin are tracked while satisfying constraints imposed by working space and allowed cable forces of the robot. In order to fully use the simulator capabilities, we propose an approach that includes the motion platform actuation in the MPC model. The tracking performance and computation time of the algorithm are investigated in computer simulations. Furthermore, for motion simulation scenarios where the reference trajectories are not known beforehand, we derive an estimate on how much motion simulation fidelity can maximally be improved by any reference prediction scheme compared to the case when no prediction scheme is applied.
The need to measure basic aerosol parameters has increased dramatically in the last decade. This is due mainly to their harmful effect on the environment and on public health. Legislation requires that particle emissions and ambient levels, workplace particle concentrations and exposure to them are measured to confirm that the defined limits are met and the public is not exposed to harmful concentrations of aerosols.
Climate change and resultant scarcity of water are becoming major challenges for countries around the world. With the advent of Wireless Sensor Networks (WSN) in the last decade and a relatively new concept of Internet of Things (IoT), embedded systems developers are now working on designing control and automation systems that are lower in cost and more sustainable than the existing telemetry systems for monitoring. The Indus river basin in Pakistan has one of the world's largest irrigation systems and it is extremely challenging to design a low-cost embedded system for monitoring and control of waterways that can last for decades. In this paper, we present a hardware design and performance evaluation of a smart water metering solution that is IEEE 802.15.4-compliant. The results show that our hardware design is as powerful as the reference design, but allows for additional flexibility both in hardware and in firmware. The indigenously designed solution has a power added efficiency (PAE) of 24.7% that is expected to last for 351 and 814 days for nodes with and without a power amplifier (PA). Similarly, the results show that a broadband communication (434 MHz) over more than 3km can be supported, which is an important stepping stone for designing a complete coverage solution of large-scale waterways.
Due to climate change and scarcity of water reservoirs, monitoring and control of irrigation systems is now becoming a major focal area for researchers in Cyber-Physical Systems (CPS). Wireless Sensor Networks (WSNs) are rapidly finding their way in the field of irrigation and play the key role as data gathering technology in the domain of IoT and CPS. They are efficient for reliable monitoring, giving farmers an edge to take precautionary measures. However, designing an energy-efficient WSN system requires a cross-layer effort and energy-aware routing protocols play a vital role in the overall energy optimization of a WSN. In this paper, we propose a new hierarchical routing protocol suitable for large area environmental monitoring such as large-scale irrigation network existing in the Punjab province of Pakistan. The proposed protocol resolves the issues faced by traditional multi-hop routing protocols such as LEACH, M-LEACH and I-LEACH, and enhances the lifespan of each WSN node that results in an increased lifespan of the whole network. We used the open-source NS3 simulator for simulation purposes and results indicate that our proposed modifications result in an average 27.8% increase in lifespan of the overall WSN when compared to the existing protocols.
eTPL: An Enhanced Version of the TLS Presentation Language Suitable for Automated Parser Generation
(2017)
The specification of the Transport Layer Security (TLS) protocol defines its own presentation language used for the purpose of semi-formally describing the structure and on-the-wire format of TLS protocol messages. This TLS Presentation Language (TPL) is more expressive and concise than natural language or tabular descriptions, but as a result of its limited objective has a number of deficiencies. We present eTPL, an enhanced version of TPL that improves its expressiveness, flexibility, and applicability to non-TLS scenarios. We first define a generic model that describes the parsing of binary data. Based on this, we propose language constructs for TPL that capture important information which would otherwise have to be picked manually from informal protocol descriptions. Finally, we briefly introduce our software tool etpl-tool which reads eTPL definitions and automatically generates corresponding message parsers in C++. We see our work as a contribution supporting sniffing, debugging, and rapid-prototyping of wired and wireless communication systems.
The paper describes the hardware and software architecture of the developed multi MEMS sensor prototype module, consisting of ARM Cortex M4 STM32F446 microcontroller unit, five 9-axis inertial measurement units MPU9255 (3D accelerometer, 3D gyroscope, 3D magnetometer and temperature sensor) and a BMP280 barometer. The module is also equipped with WiFi wireless interface (Espressif ESP8266 chip). The module is constructed in the form of a truncated pyramid. Inertial sensors are mounted on a special basement at different angles to each other to eliminate hardware sensors drifts and to provide the capability for self-calibration. The module fuses information obtained from all types of inertial sensors (acceleration, rotation rate, magnetic field and air pressure) in order to calculate orientation and trajectory. It might be used as an Inertial Measurement Unit, Vertical Reference Unit or Attitude and Heading Reference System.
The low cost and small size of MEMS inertial sensors allows their combination into a multi sensor module in order to improve performance. However the different linear accelerations measured on different places on a rotating rigid body have to be considered for the proper fusion of the measurements. The errors in measurement of MEMS inertial sensors include deterministic imperfection, but also random noise. The gain in accuracy of using multiple sensors depends strongly on the correlation between these errors from the different sensors. Although for sensor fusion it usually assumed that the measurement errors of different sensors are uncorrelated, estimation theory shows that for the combination of the same type of sensors actually a negative correlation will be more beneficial. Therefore we describe some important and often neglected considerations for the combination of several sensors and also present some preliminary results with regard to the correlation of measurements from a simple multi sensor setup.
A novel approach of a test environment for embedded networking nodes has been conceptualized and implemented. Its basis is the use of virtual nodes in a PC environment, where each node executes the original embedded code. Different nodes run in parallel, connected via so-called virtual channels. The environment allows to modifying the behavior of the virtual channels as well as the overall topology during runtime to virtualize real-life networking scenarios. The presented approach is very efficient and allows a simple description of test cases without the need of a network simulator. Furthermore, it speeds up the process of developing new features as well as it supports the identification of bugs in wireless communication stacks. In combination with powerful test execution systems, it is possible to create a continuous development and integration flow.
Heart rhythm model and simulation of electrophysiological studies and high-frequency ablations
(2017)
Background: The simulation of complex cardiologic structures has the potential to replace clinical studies due to its high efficiency regarding time and costs. Furthermore, the method is more careful for the patients’ health than the conventional ways. The aim of the study was to create an anatomic CAD heart rhythm model (HRM) as accurate as possible, and to show its usefulness for cardiac electrophysiological studies (EPS) and high-frequency (HF) ablations.
Methods: All natural heart components of the new HRM were based on MRI records, which guaranteed electronic functionality. The software CST (Computer Simulation Technology, Darmstadt) was used for the construction, while CST’s material library assured genuine tissue properties. It should be applicable to simulate different heart rhythm diseases as well as various diffusions of electromagnetic fields, caused by electrophysiological conduction, inside the heart tissue.
Results: It was achievable to simulate normal sinus rhythm and fourteen different heart rhythm disturbance with different atrial and ventricular conduction delays. The simulated biological excitation of healthy and sick HRM were plotted by simulated electrodes of four polar right atrial catheter, six polar His bundle catheter, ten polar coronary sinus catheter, four polar ablation catheter and eight polar transesophageal left cardiac catheter (Fig.). Accordingly, six variables were rebuilt and inserted into the anatomic HRM in order to establish heart catheters for ECG monitoring and HF ablation. The HF ablation catheters made it possible to simulate various types of heart rhythm disturbance ablations with different HF ablation catheters and also showed a functional visualisation of tissue heating. The use of tetrahedral meshing HRM made it attainable to store the results faster accompanied by a higher degree of space saving. The smart meshing function reduced unnecessary high resolutions for coarse structures.
Conclusions: The new HRM for EPS simulation may be additional useful for simulation of heart rhythm disturbance, cardiac pacing, HF ablation and for locating and identification of complex fractioned signals within the atrium during atrial fibrillation HF ablation.
Background: The electrical field (E-field) of the biventricular (BV) stimulation is essential for the success of cardiac resynchronization therapy (CRT) in patients with cardiac insufficiency and widened QRS complex. 3D modeling allows the simulation of CRT and high frequency (HF) ablation.
Purpose: The aim of the study was to model different pacing and ablation electrodes and to integrate them into a heart model for the static and dynamic simulation of BV stimulation and HF ablation in atrial fibrillation (AF).
Methods: The modeling and simulation was carried out using the electromagnetic simulation software. Five multipolar left ventricular (LV) electrodes, one epicardial LV electrode, four bipolar right atrial (RA) electrodes, two right ventricular (RV) electrodes and one HF ablation catheter were modeled. Different models of electrodes were integrated into a heart rhythm model for the electrical field simulation (fig.1). The simulation of an AV node ablation at CRT was performed with RA, RV and LV electrodes and integrated ablation catheter with an 8 mm gold tip.
Results: The RV and LV stimulation were performed simultaneously at amplitude of 3 V at the LV electrode and 1 V at the RV electrode, each with a pulse width of 0.5 ms. The far-field potentials generated by the BV stimulations were perceived by the RA electrode. The far-field potential at the RA electrode tip was 32.86 mV. A far-field potential of 185.97 mV resulted at a distance of 1 mm from the RA electrode tip. AV node ablation was simulated with an applied power of 5 W at 420 kHz at the distal 8 mm ablation electrode. The temperature at the catheter tip was 103.87 ° C after 5 s ablation time, 44.17 ° C from the catheter tip in the myocardium and 37.61 ° C at a distance of 2 mm. After 10 s, the temperature at the three measuring points described above was 107.33 ° C, 50.87 ° C, 40.05 ° C and after 15 seconds 118.42 ° C, 55.75 ° C and 42.13 ° C.
Conclusions: Virtual heart and electrode models as well as the simulations of electrical fields and temperature profiles allow the static and dynamic simulation of atrial synchronous BV stimulation and HF ablation at AF. The 3D simulation of the electrical field and temperature profile may be used to optimize the CRT and AF ablation.
A novel approach of a testbed for embedded networking nodes has been conceptualized and implemented. It is based on the use of virtual nodes in a PC environment, where each node executes the original embedded code. Different nodes are running in parallel and are connected via so-called virtual interfaces. The presented approach is very efficient and allows a simple description of test cases without the need of a network simulator. Furthermore, it speeds up the process of developing new features.
In this work, we consider a duty-cycled wireless sensor network with the assumption that the on/off schedules are uncoordinated. In such networks, as all nodes may not be awake during the transmission of time synchronization messages, nodes will require to re-transmit the synchronization messages. Ideally a node should re-transmit for the maximum sleep duration to ensure that all nodes are synchronized. However, such a proposition will immensely increase the energy consumption of the nodes. Such a situation demands that there is an upper bound of the number of retransmissions. We refer to the time a node spends in re-transmission of the control message as broadcast duration. We ask the question, what should be the broadcast duration to ensure that a certain percentage of the available nodes are synchronized. The problem to estimate the broadcast duration is formulated so as to capture the probability threshold of the nodes being synchronized. Results show the proposed analytical model can predict the broadcast duration with a given lower error margin under real world conditions, thus demonstrating the efficiency of our solution.
IPv6 over resource-constrained devices (6Lo) emerged as a de-facto standard for the Internet of Things (IoT) applications especially in home and building automation systems. We provide results of an investigation of the applicability of 6LoWPAN with RPL mesh networks for home and building automation use cases. The proper selection of Trickle parameters and neighbor reachable time-outs is important in the RPL protocol suite to respond efficiently to any path failure. These parameters were analyzed in the context of energy consumption w.r.t the number of control packets. The measurements were performed in an Automated Physical Testbeds (APTB). The results match the recommendation by RFC 7733 for selecting various parameters of RPL protocol suite. This paper shows the relationship between various RPL parameters and control traffic overhead during network rebuild. Comparative measurement results with Bluetooth Low Energy (BLE) in this work showed that 6Lo with RPL outperformed BLE in this use case with less control traffic overheads.
In the last decade, IPv6 over Low power Wireless Personal Area Networks (IEEE802.15.4), also known as 6LoWPAN, has well evolved as a primary contender for short range wireless communications and holds the promise of an Internet of Things, which is completely based on the Internet Protocol. The authors' team has developed a 6LoWPAN protocol stack in C language, the stack without the necessity to use a specific design environment or operating system. It is highly flexible, modular, and portable and can be enhanced by several interesting modules, like a Wake-On-Radio-(WOR) MAC layer or a TLS1.2 based security sublayer. The stack is made available as open source at https://github.com/hso-esk/emb6. It was extensively tested on the Automated Physical Testbed (APTB) for Wireless Systems, which is available in the authors' lab and allows a flexible setup and full control of arbitrary topologies. The results of the measurements demonstrate a very good stability and short-term with long-term performance also under dynamic conditions.
Due to its numerous application fields and benefits, virtualization has become an interesting and attractive topic in computer and mobile systems, as it promises advantages for security and cost efficiency. However, it may bring additional performance overhead. Recently, CPU virtualization has become more popular for embedded platforms, where the performance overhead is especially critical. In this article, we present the measurements of the performance overhead of the two hypervisors Xen and Jailhouse on ARM processors in the context of the heavy load “Cpuburn-a8” application and compare it to a native Linux system running on ARM processors.
This paper focuses on appropriately measuring the accuracy of forecasts of load behavior and renewable generation in micro-grid operation. Common accuracy measures like the root mean square of the error are often difficult to interpret for system design, as they describe the mean accuracy of the forecast. Micro-grid systems, however, have to be designed to handle also worst case situations. This paper therefore suggests two error measures that are based on the maximum function and that better allow understanding worst case requirements with respect to balancing power and balancing energy supply.
In this paper, we present a frame synchronization method which consists of the non-orthogonal superposition of a synchronization sequence and the data. We derive the optimum detection criterion and compare it to the classical sequential concatenation of synchronization and data sequences. Computer simulations confirm the benefits of the non-orthogonal allocation for the case of short frames, which makes this technique particularly suited for the increasingly important regime of low latency and ultra- reliable communication.
Finding clusters in high dimensional data is a challenging research problem. Subspace clustering algorithms aim to find clusters in all possible subspaces of the dataset where, a subspace is the subset of dimensions of the data. But exponential increase in the number of subspaces with the dimensionality of data renders most of the algorithms inefficient as well as ineffective. Moreover, these algorithms have ingrained data dependency in the clustering process, thus, parallelization becomes difficult and inefficient. SUBSCALE is a recent subspace clustering algorithm which is scalable with the dimensions and contains independent processing steps which can be exploited through parallelism. In this paper, we aim to leverage, firstly, the computational power of widely available multi-core processors to improve the runtime performance of the SUBSCALE algorithm. The experimental evaluation has shown linear speedup. Secondly, we are developing an approach using graphics processing units (GPUs) for fine-grained data parallelism to accelerate the computation further. First tests of the GPU implementation show very promising results.
Economic dispatch is a well-known optimization problem in smart grid systems which aims at minimizing the total cost of power generation among generation units while maintaining some system constraints. Recently, some distributed consensus-based approaches have been proposed to replace traditional centralized calculation. However, existing approaches fail to protect privacy of individual units like cost function parameters, generator constraints, output power levels, etc. In this paper, we show an attack against an existing consensus-based economic dispatch algorithm from [16] assuming semi-honest non-colluding adversaries. Then we propose a simple solution by combining a secure sum protocol and the consensus-based economic dispatch algorithm that guarantees data privacy under the same attacker model. Our Privacy Preserving Economic Dispatch (PPED) protocol is information-theoretically secure.
Nowadays the processing power of mobile phones, smartphones and PDAs is increasing as well as the transmission bandwidth. Nevertheless there is still the need to reduce the content and the need of processing the data. We discuss the proposals and solutions for dynamic reduction of the transmitted content. For that, device specific properties are taken into account, as much as for the aim to reduce the need of processing power at the client side to be able to display the 3D (virtual reality) data. Therefore, well known technologies, e.g. data compression are combined with new developed ideas to reach the goal of adaptive content transmission. To achieve a device dependant reduction of processing power the data have to be preprocessed at the server side or the server even has to take over functionality of weak mobile devices.