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NEXCODE is a project promoted by the European Space Agency aimed at research design development and demonstration of a receiver chain for telecomm and links in space missions including the presence of new short low-density parity-check codes for error correction. These codes have excellent performance from the error rate viewpoint but also put new challenges as regards synchronization issues and implementation. In this paper after a short review of the results obtained through numerical simulations we present an overview of the breadboard designed for practical testing and the test-plan proposed for the verification of the breadboard and the validation of the new codes and novel synchronization techniques under relevant operation conditions.
Structured Innovation with TRIZ in Science and Industry - Creating Value for Customers and Society
(2016)
We present a novel scheme for Slotted ALOHA random access systems that combines physical-layer network coding (PLNC) with multiuser detection (MUD). The PLNC and MUD are applied jointly at the physical layer to be able to extract any linear combination of messages experiencing a collision within a slot. The set of combinations extracted from a whole frame is then processed by the receiver to recover the original packets. A simple precoding stage at the transmitting terminals allows the receiver to further decrease the packet loss rate. We present results for the decoding at the physical layer as well as several performance measures at frame level, namely, throughput, packet loss rate, and energy efficiency. The results we present are promising and suggest that a cross-layer approach leveraging on the joint use of PLNC and MUD can significantly improve the performance of random access systems in the presence of slow fading.
This paper presents an overview of the coding aspects of a GNSS receiver. Coding allows detection and correction of channel-induced errors at the receiver, here the focus is on the mitigation of threats from malicious interferences. Although the effects of interference at different stages of GNSS baseband processing has been deeply analyzed in the literature, little attention was devoted to its impact on the navigation message decoding stage. Theis paper provides an introduction to the various coding schemes employed by current GNSS signals, discussing their performance in the presence of noise in terms of block-error rate. Additionally, the benefits of soft-decoding schemes for navigation message decoding are highlighted when jamming interferences are present. The proposed scheme requires estimating the noise plus interference power, yielding to enhanced decoding performances under severe jamming conditions. Finally, cryptographic schemes as a means of providing anti-spoofing for geosecurity location-based services, and their potential vulnerability are discussed, with particular emphasis on the dependence on the dependence of the scheme on successful navigation message decoding
This paper describes the new Sweaty II humanoid adult size robot trying to qualify for the RoboCup 2016 adult size humanoid competition. Based on experiences during RoboCup 2014, the Sweaty robot has been completely redesigned to a new robot Sweaty II. A major change is the use of linear actuators for the legs. Another characteristic is its indirect actuation by means of rods. This allows a variable transmission ratio depending on the angle of a joint.
After having described many different aspects of our team software in previous years, in this paper we take the freedom to describe the magmaChallenge framework provided by the magmaOffenburg team. The framework is used as a benchmark tool to run different challenges like the running challenge in 2014 or the kick accuracy challenge in 2015. This description should serve as a documentation to simplify the maintenance by the community and to add new benchmarks in the future.
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.
Lithium–oxygen cells with nonaqueous electrolyte show high overpotentials during charge, indicating asymmetric charge/discharge reaction mechanisms. We present a kinetic modeling and simulation study of the lithium–oxygen cell cycling behavior. The model includes a multistep reaction mechanism of the cell reaction (2Li + O2 ⇄ Li2O2) forming lithium peroxide by precipitation, coupled to a 1D porous-electrode transport model. We apply the model to study the asymmetric discharge/charge characteristics and analyze the influence of a redox mediator dissolved homogeneously in the liquid electrolyte. Model predictions are compared to experimental galvanostatic cycling data of cells without and with 2,2,6,6-tetramethylpiperidinyloxyl (TEMPO) as redox mediator. The predicted discharge behavior shows good agreement with the experimental results. A spatiotemporal analysis of species concentrations reveals inhomogeneous distributions of dissolved oxygen and reaction products within the cathode during discharge. The experimentally observed charge overpotentials as well as their reduction by using a redox mediator can be qualitatively reproduced with a partially irreversible reaction mechanism. However, the proposed models fail to reproduce the particular shape of the experimental charge curve with continuously increasing charge overpotential, which implies that part of the reaction mechanism is still open for investigation in future work.
Electrochemical impedance spectroscopy (EIS) is a widely-used diagnostic technique to characterize electrochemical processes. It is based on the dynamic analysis of two electrical observables, that is, current and voltage. Electrochemical cells with gaseous reactants or products (e.g., fuel cells, metal/air cells, electrolyzers) offer an additional observable, that is, the gas pressure. The dynamic coupling of current and/or voltage with gas pressure gives rise to a number of additional impedance definitions, for which we use the term electrochemical pressure impedance. It also gives rise to different experimental probing approaches. In this article we present a model-based study of electrochemical pressure impedance spectroscopy (EPIS). Possible quantifications and realizations of EPIS are discussed. The study of generic cell geometries consisting of gas reservoir, diffusion layer(s) and electrochemically active layer(s) reveals distinct spiral-shaped features in the Nyquist plot. Using the example of a sodium/oxygen (Na/O2) cell, the dynamic spatiotemporal behavior of the state variables is quantified and interpreted. Results are compared to first experimental EPIS measurements by Hartmann et al. [J. Phys. Chem. C118, 1461, 2014]. A sensitivity analysis highlights the properties of EPIS with respect to geometric, transport, and kinetic parameters. We demonstrate that EPIS is sensitive to transport parameters that are not well-accessible with standard EIS.
Nickel cobalt aluminum oxide (NCA) based lithium-ion battery electrodes exhibit a distinct asymmetry in discharge/charge behavior towards high bulk stoichiometry (low state of charge). We show that basic electrochemical relationships, that is, the Nernst equation and the Butler-Volmer equation, are able to reproduce this behavior when a two-step reaction mechanism is assumed. The two-step mechanism consists of (1) lithium-ion adsorption from the electrolyte onto the active material particle surface under electron transfer, and (2) intercalation of surface-adsorbed lithium atoms into the bulk material. The asymmetry of experimental half-cell data of an NCA electrode cycled at 0.1 C-rate can be quantitatively reproduced with this simple model. The model parameters show two alternative solutions, predicting either a saturated (highly-covered) or a depleted surface for high bulk lithiation.
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.
Cardiac resynchronization therapy is an established therapy for heart failure patients. The aim of the study was to evaluate electrical left cardiac atrioventricular delay and interventricular desynchronization in sinus rhythm cardiac resynchronization therapy responder and non-responder. Cardiac electrical desynchronization were measured by surface ECG and focused transesophageal bipolar left atrial and left ventricular ECG before implantation of cardiac resynchronization therapy defibrillators. Preoperative electrical cardiac desynchronization was 195.7 ± 46.7 ms left cardiac atrioventricular delay and 74.8 ± 24.5 ms interventricular delay in cardiac resynchronization therapy responder. Cardiac resynchronization therapy responder New York Heart Association class improved during long term biventricular pacing. Transesophageal left cardiac atrioventricular delay and interventricular delay may be additional useful parameters to improve patient selection for cardiac resynchronization therapy.
Proton Exchange Membrane Fuel Cells (PEMFC) are energy efficient and environmentally friendly alternatives to conventional energy conversion systems in many yet emerging applications. In order to enable prediction of their performance and durability, it is crucial to gain a deeper understanding of the relevant operation phenomena, e.g., electrochemistry, transport phenomena, thermodynamics as well as the mechanisms leading to the degradation of cell components. Achieving the goal of providing predictive tools to model PEMFC performance, durability and degradation is a challenging task requiring the development of detailed and realistic models reaching from the atomic/molecular scale over the meso scale of structures and materials up to components, stack and system level. In addition an appropriate way of coupling the different scales is required.
This review provides a comprehensive overview of the state of the art in modeling of PEMFC, covering all relevant scales from atomistic up to system level as well as the coupling between these scales. Furthermore, it focuses on the modeling of PEMFC degradation mechanisms and on the coupling between performance and degradation models.
The M-Bus protocol (EN13757) is in widespread use for metering applications within home area and neighborhood area networks, but lacks a strict specification. This may lead to incompatibilities in real-life installations and to problems in the deployment of new M-Bus networks. This paper presents the development of a novel testbed to emulate physical Metering Bus (M-Bus) networks with different topologies and to allow the flexible verification of real M-Bus devices in real-world scenarios. The testbed is designed to support device manufacturers and service technicians in test and analysis of their devices within a specific network before their installation. The testbed is fully programmable, allowing flexible changes of network topologies, cable lengths and types. Itis easy to use, as only the master and the slaves devices have to be physically connected. This allows to autonomously perform multiple tests, including automated regression tests. The testbed is available to other researchers and developers. We invite companies and research institutions to use this M-Bus testbed to increase the common knowledge and real-world experience.
MITK-OpenIGTLink for combining open-source toolkits in real-time computer-assisted interventions
(2016)
PURPOSE:
Due to rapid developments in the research areas of medical imaging, medical image processing and robotics, computer-assisted interventions (CAI) are becoming an integral part of modern patient care. From a software engineering point of view, these systems are highly complex and research can benefit greatly from reusing software components. This is supported by a number of open-source toolkits for medical imaging and CAI such as the medical imaging interaction toolkit (MITK), the public software library for ultrasound imaging research (PLUS) and 3D Slicer. An independent inter-toolkit communication such as the open image-guided therapy link (OpenIGTLink) can be used to combine the advantages of these toolkits and enable an easier realization of a clinical CAI workflow.
METHODS:
MITK-OpenIGTLink is presented as a network interface within MITK that allows easy to use, asynchronous two-way messaging between MITK and clinical devices or other toolkits. Performance and interoperability tests with MITK-OpenIGTLink were carried out considering the whole CAI workflow from data acquisition over processing to visualization.
RESULTS:
We present how MITK-OpenIGTLink can be applied in different usage scenarios. In performance tests, tracking data were transmitted with a frame rate of up to 1000 Hz and a latency of 2.81 ms. Transmission of images with typical ultrasound (US) and greyscale high-definition (HD) resolutions of [Formula: see text] and [Formula: see text] is possible at up to 512 and 128 Hz, respectively.
CONCLUSION:
With the integration of OpenIGTLink into MITK, this protocol is now supported by all established open-source toolkits in the field. This eases interoperability between MITK and toolkits such as PLUS or 3D Slicer and facilitates cross-toolkit research collaborations. MITK and its submodule MITK-OpenIGTLink are provided open source under a BSD-style licence ( http://mitk.org )