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Enabling ultra-low latency is one of the major drivers for the development of future cellular networks to support delay sensitive applications including factory automation, autonomous vehicles and tactile internet. Narrowband Internet of Things (NB-IoT) is a 3 rd Generation Partnership Project (3GPP) Release 13 standardized cellular network currently optimized for massive Machine Type Communication (mMTC). To reduce the latency in cellular networks, 3GPP has proposed some latency reduction techniques that include Semi Persistent Scheduling (SPS) and short Transmission Time Interval (sTTI). In this paper, we investigate the potential of adopting both techniques in NB-IoT networks and provide a comprehensive performance evaluation. We firstly analyze these techniques and then implement them in an open-source network simulator (NS3). Simulations are performed with a focus on Cat-NB1 User Equipment (UE) category to evaluate the uplink user-plane latency. Our results show that SPS and sTTI have the potential to greatly reduce the latency in NB-IoT systems. We believe that both techniques can be integrated into NB-IoT systems to position NB-IoT as a preferred technology for low data rate Ultra-Reliable Low-Latency Communication (URLLC) applications before 5G has been fully rolled out.
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.
Sowohl Angebot als auch Nachfrage nach Videos mit Lehrinhalt verzeichnen aktuell ein nahezu explosionsartiges Wachstum; MOOCs machen dabei jedoch nur einen geringen Anteil aus. Während Studierende einen positiven Effekt von Lehrvideos auf den eigenen Lernerfolg wahrnehmen, ist dieser bei objektiver Prüfung jedoch oft nicht nachweisbar. Für Dozenten eröffnet dies ein Spannungsfeld, für dessen Lösung dieser Beitrag die im Selbstversuch erprobte Möglichkeit der Produktion von Kurzvideos und deren Veröffentlichung auf YouTube vorstellt.
Kundendaten im E-Commerce – Optimierungspotenzial im Checkout-Prozess des deutschen Online-Handels
(2023)
Die Gestaltung eines benutzungsfreundlichen Checkout-Prozesses ist für den Erfolg des E-Commerce von großer Bedeutung. Die Abfrage der Kundendaten bildet einen wichtigen Teil der Customer Journey. Auf der einen Seite wollen die Handelsunternehmen so viel wie möglich über ihre Kundschaft erfahren, um möglichst zielgenaue Angebote und Marketingmaßnahmen ausspielen und das perfekte Einkaufserlebnis generieren zu können. Auf der anderen Seite möchten sich die Kundinnen und Kunden beim Online-Shopping auf den Kauf konzentrieren und erwarten einen reibungslosen Ablauf. Der Checkout-Prozess ist in diesem Zusammenhang ein kritischer Punkt. Dies spiegelt sich auch in den hohen Warenkorbabbruchraten wider. Um Online-Shoppende nachhaltig zu begeistern, gibt es noch viel Raum für Verbesserungen. Mit dem Ziel, den Status quo im deutschen Online-Handel besser zu verstehen und Usability und User Experience für eine höhere Konvertierungsrate zu optimieren, untersuchte die hier vorgestellte Forschungsarbeit den Anmelde- und Checkout-Prozess der 100 umsatzstärksten Online-Shops in Deutschland. Es werden die Ergebnisse der Studie präsentiert und aufgezeigt, an welchen Stellen Optimierungspotenzial besteht – bspw. bei zu komplizierten Formularen, unnötigen Datenabfragen oder erzwungenen Registrierungen – sowie Vorschläge für die Praxis des Online-Handels diskutiert.
Fallstudien sollen theoretische Lerninhalte zu Konzepten von Business Intelligence und Data Warehousing veranschaulichen und in einen praxisnahen Kontext bringen. Außerdem sollen Studierende umsetzungsorientierte Kompetenzen mit praxisrelevanten Systemen erwerben. Um diese Kompetenzen abzuprüfen und um die Auseinandersetzung mit Software und Konzepten zu vertiefen, haben sich Projekte als Ergänzung zu Fallstudien und Klausuren vielfach bewährt. Der Vortrag stellt dar, welche Möglichkeiten Dozierende im Rahmen der vom UCC zur Verfügung gestellten Plattform SAP Data Warehouse Cloud (SAP DWC) haben, um studentische Projekte zu Data Warehousing und Analytics durchzuführen. Der Autor berichtet über seine Erfahrung aus der Betreuung von über 30 Projekten mit SAP DWC aus verschiedenen Studiengängen seit 2020. Neben einer Übersicht über die von Studierenden gewählten Themen werden ausgewählte Projektergebnisse vorgestellt. Außerdem wird auf den Modus der Durchführung sowie existierende systemseitige Limitationen eingegangen. Für Dozierende, die mit ihren Studierenden eigene Projekte erfolgreich durchführen möchten, werden konkrete Hinweise und Maßnahmen dargestellt.
Durch den verstärkten Einsatz von EDV-Geräten an den Arbeitsplätzen in Büroräumen stiegen die flächenbezogenen inneren Kühllasten deutlich an. Für die Arbeitsplätze in Fensternähe müssen EDV-gerechte Lichtverhältnisse vorhanden sein. Es werden Versuchsergebnisse eines neu entwickelten Kühlkonvektors im Fensterbereich im Zusammenhang mit Innenjalousien vorgestellt. Dieser Kühlkonvektor eignet sich auch für den kombinierten Einsatz mit Kühldecken und raumlufttechnischen (RLT)-Anlagen, wie weitere Versuche bestätigen. Der Kühlkonvektor kann auch beim Ersatz von Induktionsgeräten angewandt werden, die z.B. nach dem 4-Leiter-Prinzip angeschlossen sind. Die Untersuchungen haben gezeigt, daß mit der Kombination von Kühldecke, Kühlkonvektor und RLT-Anlage große flächenbezogene Kühllasten abgeführt werden können, ohne daß dadurch die thermische Behaglichkeit negativ beeinflußt wird. Der Luftstrom läßt sich auf das hygienisch bzw. auf das zur Entfeuchtung notwendige Maß reduzieren, wodurch sich die Betriebskosten senken. Der Anteil der drei Komponenten an der gesamten Kühllast beträgt im Mittel: 15 % RLT-Anlage, 15 % Kühlkonvektor und 70 % Kühldecke.
Duplikaterkennung, -suche und -konsolidierung für Kunden- und Geschäftspartnerdaten, sog. „Identity Resolution“, ist die Voraussetzung für erfolgreiches Customer Relationship Management und Customer Experience Management, aber auch für das Risikomanagement zur Minimierung von Betrugsrisiken und Einhaltung regulatorischer Vorschriften und viele weitere Anwendungsfälle. Diese Systeme sind jedoch hochkomplex und müssen individuell an die kundenspezifischen Anforderungen angepasst werden. Der Einsatz lernbasierter Verfahren bietet großes Potenzial zur automatisierten Anpassung. In diesem Beitrag präsentieren wir für ein KMU praxisfähige, lernbasierte Verfahren zur automatischen Konfiguration von Business-Regeln in Duplikaterkennungssystemen. Dabei wurden für Fachanwender Möglichkeiten entwickelt, um beispielgetrieben das Match-System an individuelle Business-Regeln (u.a. Umzugserkennung, Sperrlistenabgleich) anzupassen und zu konfigurieren. Die entwickelten Verfahren wurden evaluiert und in einer prototypischen Lösung integriert. Wir konnten zeigen, dass unser Machine-Learning-Verfahren, die von einem Domainexperten erstellten Business-Regeln für das Duplikaterkennungssystem „identity“ verbessern konnte. Zudem konnte der hierzu erforderliche Zeitaufwand verkürzt werden.
The purpose of this study was to 1) compare knee joint kinematics and kinetics of fake-and-cut tasks of varying complexity in 51 female handball players and 2) present a case study of one athlete who ruptured her ACL three weeks post data collection. External knee joint moments and knee joint angles in all planes at the instance of the peak external knee abduction moment (KAM) as well as moment and angle time curves were analyzed. Peak KAMs and knee internal rotation moments were substantially higher than published values obtained during simple change-of-direction tasks and, along with flexion angles, differed significantly between the tasks. Introducing a ball reception and a static defender increased joint loads while they partially decreased again when anticipation was lacking. Our results suggest to use game-specific assessments of injury risk while complexity levels do not directly increase knee loading. Extreme values of several risk factors for a post-test injured athlete highlight the need and usefulness of appropriate screenings.
This paper presents the development of an energy harvesting solution for a driven tool holder. The tool holder environment was analysed, a test stand built and the designed electromagnetic rotation harvester was evaluated. The reported harvester is based on low cost off-the-shelf components and 3D printed parts. The utilisation of SMD coils allows easy adaptation to changing parameters of the integration area. Energy harvesting in tool holders enables predictive maintenance or condition monitoring in the industrial production. These capabilities are mandatory nowadays in regards of IIoT. A reliable energy source is key for continuous monitoring. Changing batteries becomes obsolete. The results provide useful insight for future harvesters.
Deafblindness, a form of dual sensory impairment, signifcantly impacts communication, access to information and mobility. Inde- pendent navigation and wayfnding are main challenges faced by individuals living with combined hearing and visual impairments. We developed a haptic wearable that provides sensory substitution and navigational cues for users with deafblindness by conveying vibrotactile signals onto the body. Vibrotactile signals on the waist area convey directional and proximity information collected via a fisheye camera attached to the garment, while semantic informa- tion is provided with a tapping system on the shoulders. A playful scenario called “Keep Your Distance” was designed to test the navigation system: individuals with deafblindness were “secret agents” that needed to follow a “suspect”, but they should keep an opti- mal distance of 1.5 meters from the other person to win the game. Preliminary fndings suggest that individuals with deafblindness enjoyed the experience and were generally able to follow the directional cues.
The collection of selected papers of the TRIZ Future Conference 2017 is in open access and is included to the Innovator, the journal of the European TRIZ Assocation.
The authors set the focus in this paper on the description of polarization with the help of the Jones calculus and the application of polarization in photography. Furthermore, the effect of the circular polarization filter is described by using the Jones calculus. Also, an enhancement of artistic and creative possibilities in photography through quantization or parametrization by the Jones matrices is presented.
Recently, RobustBench (Croce et al. 2020) has become a widely recognized benchmark for the adversarial robustness of image
classification networks. In it’s most commonly reported sub-task, RobustBench evaluates and ranks the adversarial robustness of trained neural networks on CIFAR10 under AutoAttack (Croce and Hein 2020b) with l∞ perturbations limited to ϵ = 8/255. With leading scores of the currently best performing models of around 60% of the baseline, it is fair to characterize this benchmark to be quite challenging. Despite it’s general acceptance in recent literature, we aim to foster discussion about the suitability of RobustBench as a key indicator for robustness which could be generalized to practical applications. Our line of argumentation against this is two-fold and supported by excessive experiments presented in this paper: We argue that I) the alternation of data by AutoAttack with l∞, ϵ = 8/255 is unrealistically strong, resulting in close to perfect detection rates of adversarial samples even by simple detection algorithms and human observers.
We also show that other attack methods are much harder to detect while achieving similar success rates. II) That results on low resolution data sets like CIFAR10 do not generalize well to higher resolution images as gradient based attacks appear to become even more detectable with increasing resolutions.
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.
Due to its potential in improving the efficiency of energy supply, smart energy metering (SEM) has become an area of interest with the surge in Internet of Things (IoT). SEM entails remote monitoring and control of the sensors and actuators associated with the energy supply system. This provides a flexible platform to conceive and implement new data driven Demand Side Management (DSM) mechanisms. The IoT enablement allows the data to be gathered and analyzed at requisite granularity. In addition to efficient use of energy resources and provisioning of power, developing countries face an additional challenge of temporal mismatch in generation capacity and load factors. This leads to widespread deployment of inefficient and expensive Uninterruptible Power Supply (UPS) solutions for limited power provisioning during resulting blackouts. Our proposed “Soft-UPS” allows dynamic matching of load and generation through a combination of managed curtailment. This eliminates inefficiencies in the energy and power value chain and allows a data-driven approach to solving a widespread problem in developing countries, simultaneously reducing both upfront and running costs of conventional UPS and storage. A scalable and modular platform is proposed and implemented in this paper. The architecture employs “WiMODino” using LoRaWAN with a “Lite Gateway” and SQLite repository for data storage. Role based access to the system through an android application has also been demonstrated for monitoring and control.
Theoretical details about optics and photonics are not common knowledge nowadays. Physicists are keen to scientifically explain ‘light,’ which has a huge impact on our lives. It is necessary to examine it from multiple perspectives and to make the knowledge accessible to the public in an interdisciplinary, scientifically well-grounded and appealing medial way. To allow an information exchange on a global scale, our project “Invisible Light” establishes a worldwide accessible platform. Its contents will not be created by a single instance, but user-generated, with the help of the global community. The article describes the infotainment portal “Invisible Light,” which stores scientific articles about light and photonics and makes them accessible worldwide. All articles are tagged with geo-coordinates, so they can be clearly identified and localized. A smartphone application is used for visualization, transmitting the information to users in real time by means of an augmented reality application. Scientific information is made accessible for a broad audience and in an attractive manner.
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.
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.
Investigation on Bowtie Antennas Operating at Very Low Frequencies for Ground Penetrating Radar
(2023)
The efficiency of Ground Penetrating Radar (GPR) systems significantly depends on the antenna performance as the signal has to propagate through lossy and inhomogeneous media. GPR antennas should have a low operating frequency for greater penetration depth, high gain and efficiency to increase the receiving power and should be compact and lightweight for ease of GPR surveying. In this paper, two different designs of Bowtie antennas operating at very low frequencies are proposed and analyzed.
Investigation of the Angle Dependency of Self-Calibration in Multiple-Input-Multiple-Output Radars
(2021)
Multiple-Input-Multiple-Output (MIMO) is a key technology in improving the angular resolution (spatial resolution) of radars. In MIMO radars the amplitude and phase errors in antenna elements lead to increase in the sidelobe level and a misalignment of the mainlobe. As the result the performance of the antenna channels will be affected. Firstly, this paper presents analysis of effect of the amplitude and phase errors on angular spectrum using Monte-Carlo simulations. Then, the results are compared with performed measurements. Finally, the error correction with a self-calibration method is proposed and its angle dependency is evaluated. It is shown that the values of the errors change with an incident angle, which leads to a required angle-dependent calibration.
Skin cancer detection proves to be complicated and highly dependent on the examiner’s skills. Millimeter-wave technologies seem to be a promising aid for the detection of skin cancer. The different water content of the skin area affected by cancer compared to healthy skin changes its reflective property. Due to limited available resources on the dielectric properties of skin cancer, especially in comparison to surrounding healthy skin, accurate simulations and evaluations are quite challenging. Therefore, comparing different results for different approaches and starting points can be difficult. In this paper, the Effective Medium Theory is applied to model skin cancer, which provides permittivity values dependent on the water content.
A fundamental and still largely unsolved question in the context of Generative Adversarial Networks is whether they are truly able to capture the real data distribution and, consequently, to sample from it. In particular, the multidimensional nature of image distributions leads to a complex evaluation of the diversity of GAN distributions. Existing approaches provide only a partial understanding of this issue, leaving the question unanswered. In this work, we introduce a loop-training scheme for the systematic investigation of observable shifts between the distributions of real training data and GAN generated data. Additionally, we introduce several bounded measures for distribution shifts, which are both easy to compute and to interpret. Overall, the combination of these methods allows an explorative investigation of innate limitations of current GAN algorithms. Our experiments on different data-sets and multiple state-of-the-art GAN architectures show large shifts between input and output distributions, showing that existing theoretical guarantees towards the convergence of output distributions appear not to be holding in practice.
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.
Data is ever increasing in the computing world. Due to advancement of cloud technology the dynamics of volumes of data and its capacity has increased within a short period of time and will keep increasing further. Providing transparency, privacy, and security to the cloud users is becoming more and more challenging along with the volume of data and use of cloud services. We propose a new approach to address the above mentioned challenge by recording the user events in the cloud ecosystem into log files and applying MAR principle namely 1) Monitoring 2) Analyzing and 3) Reporting.
Background: Cardiac resynchronization therapy (CRT) with biventricular (BV) pacing is an established therapy for heart failure (HF) patients (P) with sinus rhythm, reduced left ventricular (LV) ejection fraction (EF) and electrical ventricular desynchronization. The aim of the study was to evaluate electrical interventricular delay (IVD) and left ventricular delay (LVD) in right ventricular (RV) pacemaker pacing before upgrading to CRT BV pacing.
Methods: HF P (n=11, age 69.0 ± 7.9 years, 1 female, 10 males) with DDD pacemaker (n=10), DDD defibrillator (n=1), RV pacing, New York Heart Association (NYHA) class 3.0 ± 0.2 and 24.5 ± 4.9 % LVEF were measured by surface ECG and transesophageal bipolar LV ECG before upgrading to CRT defibrillator (n=8) and CRT pacemaker (n=3). IVD was measured between onset of QRS in the surface ECG and onset of LV signal in the transesophageal ECG. LVD was measured between onset and offset of LV signal in the transesophageal ECG. CRT atrioventricular (AV) and BV pacing delay were optimized by impedance cardiography.
Results: Interventricular and intraventricular desynchronization in RV pacemaker pacing were 228.2 ± 44.8 ms QRS duration, 86.5 ± 32.8ms IVD, 94.4 ± 23.8ms LVD, 2.6 ± 0.8 QRS-IVD-ratio with correlation between IVD and QRS-IVD-ratio (r=-0.668 P=0.0248) and 2.3 ± 0.7 QRS-LVD-ratio. The LVEF-IVD-ratio was 0.3 ± 0.1 with correlation between IVD and LVEF-IVD-ratio (r=-0.8063 P=0.00272) and with correlation between QRS duration and LVEF-IVD-ratio (r=-0.7251 P=0.01157). Optimal sensing and pacing AV delay were 128.3 ± 24.8 ms AV delay after atrial sensing (n=6) and 173.3 ± 40.4 ms AV delay after atrial pacing (n=3). Optimal BV pacing delay was -4.3 ± 11.3 ms between LV and RV pacing (n=7). During 30.4 ± 29.6 month CRT follow-up, the NYHA class improved from 3.1 ± 0.2 to 2.2 ± 0.3.
Conclusions: Transesophageal electrical IVD and LVD in RV pacemaker pacing may be additional useful ventricular desynchronization parameters to improve P selection for upgrading RV pacemaker pacing to CRT BV pacing.
The United Nations have declared 2015 as the International Year of Light (IYL2015) and light-based technologies [1]. As a main result, the public interest is focused on both the achievements and the new frontiers of optics and photonics. This opens up new perspectives in the teaching and training of optics and photonics. In the first part of the paper, the author presents the numerous anniversaries occurring in the International Year of Light 2015 together with their importance to the development of science and technology. In the second part, we report on an interactive video projection at the opening ceremony of the IYL2015 in Paris on January 19-20, 2015. Students of Offenburg University have established an interactive video projection which visualizes Twitter and Facebook messages posted with the hashtag #iyl2015 in a mapping technique. Thus, the worldwide community can be interactively part of the opening ceremony. Finally, upcoming global community projects related to optics and astronomy events are presented.
After the successful International Year of Light 2015, the idea of sustainability became increasingly imminent. After a preparatory year on 16 May 2018, the International Day of Light was launched for the first time. This event was celebrated with a public celebration in Paris at the UNESCO headquarters. In this paper we will present our projects dedicated to the International Day of Light in Paris. Together with a group of students from our university, we had the special opportunity to be integrated in the program of the opening ceremony at UNESCO in Paris. With our interdisciplinary projects we have tried to build a bridge between optics, photonics, art and media installations.
Not only is the number of new devices constantly increasing, but so is their application complexity and power. Most of their applications are in optics, photonics, acoustic and mobile devices. Working speed and functionality is achieved in most of media devices by strategic use of digital signal processors and microcontrollers of the new generation. Considering all these premises of media development dynamics, the authors present how to integrate microcontrollers and digital signal processors in the curricula of media technology lectures by using adequate content. This also includes interdisciplinary content that consists of using the acquired knowledge in media software. These entries offer a deeper understanding of photonics, acoustics and media engineering.
The use of artificial intelligence continues to impact a broad variety of domains, application areas, and people. However, interpretability, understandability, responsibility, accountability, and fairness of the algorithms' results - all crucial for increasing humans' trust into the systems - are still largely missing. The purpose of this seminar is to understand how these components factor into the holistic view of trust. Further, this seminar seeks to identify design guidelines and best practices for how to build interactive visualization systems to calibrate trust.
Artificial intelligence (AI), and in particular machine learning algorithms, are of increasing importance in many application areas but interpretability and understandability as well as responsibility, accountability, and fairness of the algorithms' results, all crucial for increasing the humans' trust into the systems, are still largely missing. Big industrial players, including Google, Microsoft, and Apple, have become aware of this gap and recently published their own guidelines for the use of AI in order to promote fairness, trust, interpretability, and other goals. Interactive visualization is one of the technologies that may help to increase trust in AI systems. During the seminar, we discussed the requirements for trustworthy AI systems as well as the technological possibilities provided by interactive visualizations to increase human trust in AI.
The title expresses goals the Kansas Geological Survey (KGS) has been working toward for some time. This report extends concepts and objectives developed while working on an earlier effort for effective interactive digital maps on the Internet. That work was reported to the 1998 DMT Workshop in Champaign, Illinois (Ross, 1998). The current project goes beyond previous efforts that focused on methods for serving the contents of a geographic information system (GIS); the points, lines, and polygons representing features of the digital geologic map and the data in the attribute tables of the GIS describing those features.
A simple model is introduced that describes the interaction of surface acoustic waves (SAWs) with a 2D periodic array of objects on the surface that give rise to internal resonances. Such objects may be high-aspect ratio structures like micro-pillars fabricated of a material different from that of the substrate. The model allows for an approximate determination of the band structure for the acoustic modes in such systems. Results are presented for the dependence on structural parameters of a total bandgap in the non-radiative regime of a semi-infinite substrate, and it is shown how the frequency and radiation damping of vibrational modes can be determined that are associated with defects in the periodic 2D array.
The automatic processing of handwritten forms remains a challenging task, wherein detection and subsequent classification of handwritten characters are essential steps. We describe a novel approach, in which both steps - detection and classification - are executed in one task through a deep neural network. Therefore, training data is not annotated by hand, but manufactured artificially from the underlying forms and yet existing datasets. It can be demonstrated that this single-task approach is superior in comparison to the state-of-the-art two task approach. The current study focuses on hand-written Latin letters and employs the EMNIST data set. However, limitations were identified with this data set, necessitating further customization. Finally, an overall recognition rate of 88.28% was attained on real data obtained from a written exam.
Additive manufacturing processes have evolved rapidly in recent years and now offer a wide range of manufacturing technologies and workable materials. This range from plastics and metals to paper and even polymer plaster composites. Due to the layer by layer structure of the components the additive processes have in comparison with conventional manufacturing processes the advantage of freedom of design, that means the simple implementation of complex geometries. Moreover, the additive processes provide the advantage of reduced consumption of resources, since essentially only the material is consumed, which is required for the actual component, since no waste in the form of chips is produced. In order to use these advantages, the potentials of additive manufacturing and the requirements of sustainable design must already be observed in the product development process. So the design of the components and products must be made so as little as possible construction and supporting material is required for the generative production and therefore little resources are consumed. Also, all steps of the additive manufacturing process must be considered properly, that includes the post processing. This allows components be designed so that for instance the effort for removing the support structure is considerably reduced. This leads to a significant reduction in manufacturing time and thus energy consumption. The implementation of these potentials in product development can be demonstrated by means of a multiple-stages model. A case study shows how this model is applied in the training of Master students in the field of product development. In a workshop the students work as a group while implementing the task of developing a miniature racing car under the rules of sustainable design in compliance with the boundary conditions for an additive manufacturing. In this case, Fused Deposition Modelling FDM using plastics as a building material is applied. The results show how the students have dealt with the different requirements and how they have implemented them in product development and in the subsequent additive manufacturing.
Blockchain frameworks enable the immutable storage of data. A still open practical question is the so called "oracle" problem, i.e. the way how real world data is actually transferred into and out of a blockchain while preserving its integrity. We present a case study that demonstrates how to use an existing industrial strength secure element for cryptographic software protection (Wibu CmDongle / the "dongle") to function as such a hardware-based oracle for the Hyperledger blockchain framework. Our scenario is that of a dentist having leased a 3D printer. This printer is initially supplied with an amount of x printing units. With each print action the local unit counter on the attached dongle is decreased and in parallel a unit counter is maintained in the Hyperledger-based blockchain. Once a threshold is met, the printer will stop working (by means of the cryptographically protected invocation of the local print method). The blockchain is configured in such a way that chaincode is executed to increase the units again automatically (and essentially trigger any payment processes). Once this has happened, the new unit counter value will be passed from the blockchain to the local dongle and thus allow for further execution of print jobs.
Wireless Sensor Networks (WSN) have emerged as interesting topic in the research community due to its manifold applications. One of the main challenges of this field is the energy consumption of the nodes, which typically is quite restricted due to the required lifetime of such WSNs. To solve that problem several energy-saving MAC protocols have been developed so far. One of them recently presented by the authors is the so-called SmartMAC as an extension to the IEEE802.15.4 standard. In this paper, we present the implementation details of the porting of the SmartMAC protocol to the discrete event network simulator NS3. We develop this module for NS3 to simulate the performance, multi node execution, and multi node configuration. Along with this model, we also present an energy model for the evaluation of the energy consumption. The current implementation in NS3 is based on the LR-WPAN (Low-Rate Wireless Personal Area Networks) as specified by the IEEE802.15.4 (2006) standard. The simulation results show that the SmartMAC with its sleep and wake-up mechanisms for the transceivers, is significantly more efficient than the current NS3 MAC (Medium Access Control) scheme.
Auch wenn kaum eine andere Branche in Deutschland durch die weltweite Finanzkrise so stark getroffen wurde wie der Maschinenbau, gehört dieser nach wie vor zu den erfolgreichsten Branchen (vgl. VDMA 2010). In vielen Produktsegmenten sind deutsche Maschinenbauer Weltmarktführer. Jedoch stehen sie seit einigen Jahren Herausforderungen gegenüber, die zu einem Umdenken und einer Neuausrichtung führen. Insbesondere das nach wie vor existente Problem der Produktpiraterie sowie die zumeist aus den asiatischen Räumen eingetretenen Wettbewerber, die für einen enormen Preisdruck sorgen, haben in den letzten Jahren dazu geführt, dass Standardmaschinen nur noch eine geringe Profitabilität aufweisen. Mit produktbegleitenden Dienstleistungen (Services) hingegen lasst sich mit durchschnittlich 21 % eine rund viermal so hohe operative Marge realisieren wie mit Maschinen (vgl. Schmiedeberg/Strahle/Bendig 2010, S. 3). Annahmen gehen davon aus, dass Services das Potenzial haben, einen Umsatzanteil von bis zu 35 % und damit einen Gewinnanteil von bis zu 60 % zu erreichen.
Massiv- Heiz-/Kühldecken bestehen im wesentlichen aus in der tragenden Deckenkonstruktion eingegossenen Kunststoffrohren, die je nach Jahreszeit von Heiz- bzw. Kühlwasser durchströmt verden. Das instationäre Verhalten wurde mit dem Anlagen und Simulationsprogramm TRNSYS untersucht. Anhand ausgesuchter Ergebnisse können die Anforderungen an die notwendigen Regelkonzepte abgeleitet werden. Es eignen sich für derartige Systeme, insbesondere wegen ihrer großen Speicherfähigkeit und damit Trägheit, modifizierende selbstadaptierende Regler. Aufgrund der großen Trägheit der Massivdecke ist eine direkte außentemperaturgeführte Vorlauftemperaturregelung des Wasserstromes nicht sinnvoll. Es sollte ein selbstadaptierendes Regelsystem verwendet werden, das anhand der vorangegangenen Lastverläufe die Gebäudekonstante und damit das Speicherverhalten der Räume ermittelt. Damit der Regelaufwand reduziert werden kann, sollen mehrere Räume als Gruppe zusammengefaßt werden. Als weitere Größe für das Regelkonzept ist die Speichertemperatur am Ende der Ladezeit zu messen und in das Programm mit einzubinden.
Having 22 GW of nominal power installed Germany is the leading nation in wind energy conversion. While the number of suitable installation sites ashore is limited, and the average windspeed and thus the utilization level offshore is significantly higher, more and more offshore wind farms are planned. In order to reduce the cost of building the foundations and of connecting the wind turbines to the power grid, the single plant is designed as powerful as possible and therefore the components become huge and weighty. For instance: In order to lift the nacelle with around 500 tons of weight up on the tower - which can be up to 120 m above the water level - at the time special ships and cranes are designed and built. But those firstly will be very expensive and secondly will be available only on a limited scale. Hence the installation cost of those huge wind turbines significantly influence the rentability of a wind farm. Against this background a joint research project supported by the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU) was started comprising the project partners Ed. Züblin AG, Berg-idl GmbH (an engineering company and a maker of special purpose machines in Altlußheim, Germany), the IPEK (institute for product development) at the university of Karlsruhe and the Hochschule Offenburg, university of applied science. Project target is the conceptual design of a heavy-duty elevator, which can be used to install the tower segments and the nacelle of a wind turbine offshore without a crane. The most relevant challenges in this context result of holding up extreme loads by means of comparatively filigree carrying structures. The paper shows some examples of structural analysis and optimization work accomplished during the project. For the structural analysis of the heavy loaded components ANSYS workbench was used. The development process was also supported by optimization tools like TOSCA and OPTIMUS. The linking of the FE solver and the optimizer provides important hints concerning improvement of the topology and the dimensions of the components. Examples of designs illustrate the development process and the methods applied.
The additive manufacturing processes have developed significantly in recent years. Currently, new generative processes are coming onto the market. Likewise, the number of available materials that can be processed using additive processes is steadily increasing. Therefore, an important task is to integrate these new processes and materials into the university education of engineers. Due to the rapid change and the constant development in the field of additive manufacturing, a pure transfer of knowledge is not expedient, because this obsolete very quickly. Rather, the students should be enabled to use their skills in such a way that they can always handle new technologies and materials independently and meaningfully.
In this paper, therefore, a new course is developed in which the students largely independently work with additive manufacturing processes. For this purpose, teams of four to five students from different technical programs are formed. The teams have the task of developing and manufacturing a product using additive processes. The goal is to create a powerful product by taking into account the optimization of costs and use of resources.
As an example, the development and additive manufacturing of an ornithopter (aircraft that flies by flapping its wings) will be presented in this contribution. The students have to analyze and optimize the mechanics and aerodynamics of the aircraft. In addition, the rules for production-oriented design must be determined and applied. Further more, they should assess the costs and material consumption during development and production.
This contribution shows how the students have achieved the different learning outcomes. In addition, it becomes clear how the students independently acquired and applied their knowledge in development, design and additive manufacturing. Also, it will be demonstrated how much time the students spent on learning the different technologies.
Printed electronics (PE) is a fast growing technology with promising applications in wearables, smart sensors and smart cards since it provides mechanical flexibility, low-cost, on-demand and customizable fabrication. To secure the operation of these applications, True Random Number Generators (TRNGs) are required to generate unpredictable bits for cryptographic functions and padding. However, since the additive fabrication process of PE circuits results in high intrinsic variation due to the random dispersion of the printed inks on the substrate, constructing a printed TRNG is challenging. In this paper, we exploit the additive customizable fabrication feature of inkjet printing to design a TRNG based on electrolyte-gated field effect transistors (EGFETs). The proposed memory-based TRNG circuit can operate at low voltages (≤ 1 V ), it is hence suitable for low-power applications. We also propose a flow which tunes the printed resistors of the TRNG circuit to mitigate the overall process variation of the TRNG so that the generated bits are mostly based on the random noise in the circuit, providing a true random behaviour. The results show that the overall process variation of the TRNGs is mitigated by 110 times, and the simulated TRNGs pass the National Institute of Standards and Technology Statistical Test Suite.
The ability to detect a target signal masked by noise is improved in normal-hearing listeners when interaural phase differences (IPDs) between the ear signals exist either in the masker or in the signal. To improve binaural hearing in bilaterally implanted cochlear implant (BiCI) users, a coding strategy providing the best possible access to IPDs is highly desirable. Outcomes of a previous study (Zirn, Arndt et al. 2016) revealed that a subset of BiCI users showed improved IPD detection thresholds with the fine structure processing strategy FS4 compared to the constant rate strategy HDCIS using narrowband stimuli. In contrast, little differences between the coding strategies were found for broadband stimuli with regard to binaural speech intelligibility level differences (BILD) as an estimate of binaural unmasking. Compared to normalhearing listeners (7.5 ± 1.2 dB) BILD were small in BiCI users (around 0.5 dB with both coding strategies).
In the present work, we investigated the influence of binaural fitting parameters on BILD. In our cohort of BiCI users many were implanted with electrode arrays differing in length left versus right. Because this length difference typically corresponded to the distance of two electrode contacts the first modification of bilateral fitting was a tonotopic adjustment by deactivation of the most apical electrode contact on the side with the deeper inserted array (tonotopic approach).
The second modification was the isolation of the residual, most apical electrode contacts by deactivation of the basally adjacent electrode contact on each side (tonotopic sparse approach). Applying these modifications, BILD improved by up to 1.5 dB.
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.
Landing heel first has been associated with elevated external knee abduction moments (KAM), thereby potentially increasing the risk of sustaining a non-contact ACL injury. Apart from the foot strike angle, knee valgus angle (VAL) and vertical center of mass velocity at initial ground contact (IC) have been associated with increased KAM in females across different sidestep cuts. While real-time biofeedback training has been proven effective for gait retraining [4], the highly dynamic, non-cyclical nature of cutting maneuvers makes real-time feedback unsuitable and alternative approaches necessary. This study aimed at assessing the efficacy of immediate software-aided feedback on cutting technique in reducing KAM during handball-specific cutting maneuvers.
This study aims to investigate the individual response concerning BRFs for AT when the mid-sole hardness underneath the rearfoot was systematically altered. We first identified FGs based on the footwear condition that minimised the risk for AT across BRFs. We then tested the FGs for differences in anthropometrics, footwear comfort, and running characteristics.
Bei modernen Lokomotiven mit Drehstrom-Asynchronmotoren und mit bis zu 7 Megawatt Leistung, neigt das Antriebssystem bei nicht ausreichendem Kraftschluß zwischen Treibradsatz und Schiene zum 'Durchdrehen'. Bei diesem Vorgang wird nahezu die gesamte Energie zur Beschleunigung des Radsatzes eingesetzt, was zu mechanischen Schäden an den Rädern und Schienen führen kann. Beim Bremsen ist dies ähnlich, die Räder gleiten auf den Schienen, wenn zuviel Bremskraft gefordert wird. Die übertragbaren Zug- und Bremskräfte werden primär durch die Radsatzlast und den Kraftschlußbeiwert bestimmt, wobei der Verlauf der Kraftschlußkennlinie als Funktion des Schlupfs oder der Schlupfgeschwindigkeit im wesentlichen durch den Schienenzustand (naß oder trocken) bestimmt wird. Eine hohe Kraftschlußnutzung wird dann erreicht, wenn man laufend denjenigen Schlupfwert einstellt, der zum jeweiligen Kraftschlußmaximum führt. Hierzu werden in der Praxis verschiedene Konzepte und Methoden eingesetzt, es ist bis heute jedoch keine Methode bekannt, den Verlauf der Kraftschlußkennlinie meßtechnisch laufend zu erfassen oder rechentechnisch zu bestimmen. Bei der hier vorgestellten Vorgehensweise wurde der mechanische Antrieb zusammen mit dem Rad-Schiene-Kontakt als Zustandsraumodell beschrieben. Die Betrachtungen beruhen dann auf einer Frequenzganguntersuchung des eingeführten linearen Zustandsraummodells. Aufgrund der Linearisierung gelten die Ergebnisse der Frequenzgangsberechnung nur für den jeweiligen Betriebspunkt der Kraftschlußkennlinie, also für eine bestimmte Steigung. Variiert man nun die Steigung, so läßt sich der Einfluß der nichtlinearen Kraftschlußkennlinien ermitteln. Zur Messung von Frequenzgängen eignen sich insbesondere Verfahren der Orthogonalen Korrelation. Die technische Realisierung wird skizziert. Die Meßinformation ist dann die Basis für eine Regelung, die ein permanentes optimales Fahren im Kraftschlußmaximum zuläßt und zwar beim Beschleunigen und beim Bremsen. Das beschriebene Meß- und Regelungsverfahren ist derzeit in der Schweiz in der Betriebserprobung.
The present paper addresses the research question: What recommendations for action and potential adjustments should an online magazine for beauty and fashion implement in order to make affiliate articles in these sections even more appealing to the target group and provide added value for them?
To be able to answer this research question, three hypotheses were defined and tested with using qualitative and quantitative research. The qualitative research consisted of user experience testings, where four affiliate articles in the fields of beauty and fashion were tested with 13 participants. The quantitative research involved collecting, analyzing and evaluating data from the four affiliate articles conducted with the company's real-life target group. Based on these results, recommendations for action were derived, which should not only improve the quality of the content in the future, but also increase the efficiency of the implementation of those articles.
Increased knowledge transfer through the integration of research projects into university teaching
(2019)
This paper describes the integration of the research project "Characterization of Color Vision using Spectroscopy and Nanotechnology: Application to Media Photonics" into an engineering course in the field of media technology. The aim is to develop the existing learning concept towards a more research-oriented teaching. Involving students in research projects as part of the learning process provides a deeper insight into current research topics and the key elements of scientific work. This makes it easier for students to recognize the importance of the acquired theoretical knowledge for the practice, which enables them to derive new insights of their own.
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.
Autonomous humanoid robots require light weight, high torque and high speed actuators to be able to walk and run. For conventional gears with a fixed gear ratio the product of torque and velocity is constant. On the other hand desired motions require maximum torque and speed. In this paper it is shown that with a variable gear ratio it is possible to vary the relation between torque and velocity. This is achieved by introducing systems of rods and levers to move the joints of our humanoid robot ”Sweaty II”. On the basis of a variable gear ratio low speed and high torque can be achieved for those joint angles, which require this motion mode, whereas high speed and low torque can be realized for those joint angles, where it is favorable for the desired motion.
During the day-to-day exploitation of localization systems in mines, the technical staff tends to incorrectly rearrange radio equipment: positions of devices may not be accurately marked on a map or their positions may not correspond to the truth. This situation may lead to positioning inaccuracies and errors in the operation of the localization system.This paper presents two Bayesian algorithms for the automatic corrections of positions of the equipment on the map using trajectories restored by the inertial measurement units mounted to mobile objects, like pedestrians and vehicles. As a basis, a predefined map of the mine represented as undirected weighted graph was used as input. The algorithms were implemented using the Simultaneous Localization and Mapping (SLAM) approach.The results prove that both methods are capable to detect misplacement of access points and to provide corresponding corrections. The discrete Bayesian filter outperforms the unscented Kalman filter, which, however, requires more computational power.
In recent years, the additive manufacturing processes have rapidly developed. The additive manufacturing processes currently present a high-performance alternative to conventional manufacturing methods. In particular, they offer the opportunity of previously hardly imaginable design freedom, i.e. the implementation of complex forms and geometries. This capability can, for example, be applied in the development of especially light but still loadable components in automotive engineering. In addition, waste material is seldom produced in additive manufacturing which benefits a sustainable production of building components. Until now, this design freedom was barely used in the construction of technical components and products because, in doing so, both specific design guidelines for additive manufacturing and complex strength calculations must be simultaneously observed. Yet in order to fully take advantage of the additive manufacturing potential, the method of topology optimization, based on FEM simulation, suggests itself. It is with this method that components that are precisely matched and are especially light, thereby also resource-saving, can be produced. Current literature research indicates that this method is used in automotive manufacturing for reducing weight and improving the stability of both individual parts and assembly units. This contribution will study how this development method can be applied in the example of a brake mount from an experimental vehicle. In this, the conventional design is improved by means of a simulation tool for topology optimization in various steps. In an additional processing step, the smoothing of the thus developed component occurs. Finally, the component is generatively manufactured by means of selective laser melting technology. Models are manufactured using binder jetting for the demonstration of the process. It will also be determined how this weight reduction affects the CO2 emissions of a vehicle in use.
Introduction: Cardiac resynchronisation therapy (CRT) with atrioventricular (AV) and interventricular (VV) optimized biventricular pacing (BV) is an established therapy for heart failure (HF) patients with electrical interventricular conduction delay (IVCD). The aim of the study was to compare AV and VV delay optimization with cardiac output (CO) and acceleration index (ACI) impedance cardiographic (ICG) methods.
Methods: HF patients with IVCD 86.8 ± 33 ms (n=15, age 66 ± 10 years; 2 females, 13 males), New York Heart Association (NYHA) functional class 3.1 ± 0.4, left ventricular (LV) ejection fraction 21.3 ± 7.8 % and QRS duration 176.1 ± 31.7 ms underwent AV and VV delay optimization with CO and ACI methods (Cardioscreen, Medis GmbH, Ilmenau, Germany). After evaluation of optimal AV delay, we evaluated optimal VV delay during simultaneous LV and right ventricular (RV) pacing (LV=RV), LV before RV pacing (LV-RV) and RV before LV pacing (RV-LV).
Results: Optimal VV delay was -12.3 ± 25.9 ms LV-RV pacing with VV delay range from -80 ms LV-RV pacing to +20 ms RV-LV pacing and RV=LV pacing. Optimal AV delay after atrial sensing was 108.6 ± 20.3 ms (n=14) and optimal AV delay after atrial pacing 190 ± 14.1 ms (n=2) with AV delay range from 80 ms to 200 ms. RV versus BV pacing mode resulted in improvement of CO from 3.4 ± 1.2 l/min to 4.4 ± 1.4 l/min (p<0.001) and ACI from 0.667 ± 0.227 1/s² to 0.834 ± 0.282 1/s² (p<0.002). During 34 ± 26 month BV pacing, the NYHA class improved from 3.1 ± 0.4 to 2.1 ± 0.4 (p<0.001).
Conclusion: AV and VV delay optimized BV pacing acutely improve ICG CO and ACI and their NYHA class during long-term follow-up. ICG may be a simple and useful technique to optimize AV and VV delay in CRT.
The integration of additive manufacturing processes into the teaching of students is an important prerequisite for the further dissemination of this new technology. In this context, the DfAM is of particular importance. For this reason, this paper presents an approach in which a connection is made between methodical product development and practical implementation by AM. Using a model racing car as an example, students independently develop significant improvements of particular assemblies. A final evaluation shows that the students have significantly improved their skills and competencies.
Non-responder rate in cardiac resynchronization therapy (CRT) could be partly decreased by individualized parameter optimization excluding adverse hemodynamic timing. In heart failure patients with sinus rhythm, an atrial kick enables the completion of atrial contraction and may significantly enhance the ventricular filling. Compared to that, exclusion of atrial kick is a sign of suboptimal atrioventricular timing. However, the recognition of atrial kick by echocardiography will be negatively affected in patients requiring a very short or long AV delays.
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.
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.
Implementation of lightweight design in the product development process of unmanned aerial vehicles
(2017)
The development and manufacturing of unmanned aerial vehicles (UAVs) require a multitude of design rules. Thereby, additive manufacturing (AM) processes provide a number of significant advantages over conventional production methods, particularly for implementing requirements with regard to lightweight construction and sustainability. A new, promising approach is presented, with which, through the combination of very light structural elements with a ribbed construction, an attached covering by means of foil is used. This contribution develops and presents a development process that is based on various development cycles. Such cycles differ in their effort and scope within the overall development, and may only comprise one part of the development process, or the entire development process. The applicability of this development process is demonstrated within the framework of a comprehensive case study. The aim is to develop an additively manufactured product that is as light as possible in the form of a UAV, along with a sustainable manufacturing process for such product. Finally, the results of this case study are analyzed with regard to the improvement of lightweight construction.
Implementation of interdisciplinary student teams in design education for additive manufacturing
(2018)
Additive manufacturing (AM) technologies are becoming increasingly popular in all areas of product development. Therefore, it is imperative that students be taught Design for AM. However, due to the rapid development of new methods and materials for AM, it does not make sense to only teach particular design guidelines, as these can quickly become obsolete. Rather, students should acquire the competence to develop guidelines themselves, that take into account the current state of the art. Thus, they will be able to react to changing processes and new materials
in the future. In order to convey the independent development of design guidelines for additive manufacturing by students, a new concept was developed, which is presented in this contribution. In this process, the learning goal is worked out by a group of students on the basis of a practical
task. The group consists of an interdisciplinary team in order to combine different competencies and to provide different perspectives on the task. A case study will show the design and manufacture of a miniature aircraft using Fused Layer Modelling. The aim of the development is above all the design for additive manufacturing. In addition, a low use of resources in combination with lightweight construction should be achieved. In the implementation of the task, the students are confronted with challenging aerodynamic design of wings as well as with the economic evaluation of the development process. An examination of the level of knowledge before and after the case study examines the learning success.
For the past few years Low Power Wide Area Networks (LPWAN) have emerged as key technologies for the connectivity of many applications in the Internet of Things (IoT) combining low-data rates with strict cost and energy restrictions. Especially LoRa/LoRaWAN enjoys a high visibility on today’s markets, because of its good performance and its open community. Originally LoRa was designed for operation within the Sub-GHz ISM bands for Industrial, Scientific and Medical applications. However, at the end of 2018, a LoRa-based solution in the 2.4GHz ISM-band was presented promising higher bandwidths and higher data rates. Furthermore, it overcomes the limited duty-cycle prescribed by the regulations in the ISM-bands and therefore also opens doors to many novel application fields. Also, due to higher bandwidths and shorter transmission times, the use of alternative MAC layer protocols becomes very interesting, i.e. for TDMA based-approaches. Within this paper, we propose a system architecture with 2.4GHz LoRa components combining two aspects. On the one hand, we present a design and an implementation of a 2.4GHz based LoRaWAN solution that can be seamlessly integrated into existing LoRaWAN back-hauls. On the other hand, we describe deterministic setup using a Time Slotted Channel Hopping (TSCH) approach as defined in the IEEE802.15.4-2015 standard for industrial applications. Finally, measurements show the performance of the system.
Remote measurement of the physiology, so-called biotelemetry, is a key technology in the modern veterinary medicine. The usage of wireless implants has less impact on the behavior of animals than manual measurement methods and cause less disturbance than wired devices. But, common biotelemetry still uses proprietary communication and power concepts focused on small systems with one animal. Therefore, the University of Applied Sciences Offenburg is developing a low-cost RFID system called muTrans1, which is able to measure ECG, pressure, temperature, oxygen saturation and activity. The muTrans uses an own RFID sensor transponder and standardized commercial components and combines them to a scalable RFID system able to build-up RFID sensor networks with a nearly unlimited size.
In this work, we explore three deep learning algorithms apply to seismic interpolation: deep prior image (DPI), standard, and generative adversarial networks (GAN). The standard and GAN approaches rely on a dataset of complete and decimated seismic images for the training process, while the DPI method learns from a decimated image itself, without training images. We carry out two main experiments, considering 10%, 30%, and 50% of regular and irregular decimation. The first tests the optimal situation for the GAN and the standard approaches, where training and testing images are from the same dataset. The second tests the ability of GAN and standard methods to learn simultaneously from three datasets, and generalize to a fourth dataset not used during training. The standard method provides the best results in the first experiment, when the training distribution is similar to the testing one. In this situation, the DPI approach reports the second best results. In the second experiment, the standard method shows the ability to learn simultaneously and effectively three data distributions for the regular case. In the irregular case, the DPI approach is more effective. The GAN approach is the less effective of the three deep learning methods in both experiments.
This paper presents an approach for implementing an automated hit detection and score calculation system for a steel dartboard using a standard webcam. First, the rectilinear field separations of the dartboard are described mathematically by means of line slopes and are than stored. These slopes serve as a basis for later score calculation. In addition, thrown darts have to be detected and the pixel at which the dart cuts the dartboard has to be determined. When this information is known, a comparison is made using the line slopes, allowing the field number of the hit to be detected. The decision for single, double or triple hit is made by evaluating the defined colors on the dartboard. All these functions are then packaged in a Matlab GUI.
This article sets the focus on methods of information technology in the Humboldt Portal, which represents an ongoing research project to develop a virtual research environment on the Internet for the legacy of Alexander von Humboldt. Based on the experiences of developing and providing the Humboldt Digital Library (www.avhumboldt.net) for more than a decade, we defined a working plan to create an Internet portal for comprehensive access to Humboldt’s writings, no matter if documents are provided as PDF files, scan images or XML-TEI documents on external archives (Google Books, Internet Archive, Deutsches Textarchiv, Bibliotheque National de France). Going far beyond services of a digital library we will provide an information network with multimedia assets, which are containing objects like terms, paragraphs, data tables, scan images, or illustrations, together with correlated properties like thematic linkage to other objects, relevant keywords with optional synonyms and dynamic hyperlinks to related translations in different languages. So the Humboldt Portal can contribute to the key question, how to present interconnected data in an appropriate form using information technologies on the Web.
Due to the Covid-19 pandemic, the RoboCup WorldCup 2021 was held completely remotely. For this competition the Webots simulator (https://cyberbotics.com/) was used, so all teams needed to transfer their robot to the simulation. This paper describes our experiences during this process as well as a genetic learning approach to improve our walk engine to allow a more stable and faster movement in the simulation. Therefore we used a docker setup to scale easily. The resulting movement was one of the outstanding features that finally led to the championship title.
The development of Internet of Things (IoT) embedded devices is proliferating, especially in the smart home automation system. However, the devices unfortunately are imposing overhead on the IoT network. Thus, the Internet Engineering Task Force (IETF) have introduced the IPv6 Low-Power Wireless Personal Area Network (6LoWPAN) to provide a solution to this constraint. 6LoWPAN is an Internet Protocol (IP) based communication where it allows each device to connect to the Internet directly. As a result, the power consumption is reduced. However, the limitation of data transmission frame size of the IPv6 Routing Protocol for Low-power and Lossy Network’s (RPL’s) had made it to be the running overhead, and thus consequently degrades the performance of the network in terms of Quality of Service (QoS), especially in a large network. Therefore, HRPL was developed to enhance the RPL protocol to minimize redundant retransmission that causes the routing overhead. We introduced the T-Cut Off Delay to set the limit of the delay and the H field to respond to actions taken within the T-Cut Off Delay. Thus, this paper presents the comparison performance assessment of HRPL between simulation and real-world scenarios (6LoWPAN Smart Home System (6LoSH) testbed) in validating the HRPL functionalities. Our results show that HRPL had successfully reduced the routing overhead when implemented in 6LoSH. The observed Control Traffic Overhead (CTO) packet difference between each experiment is 7.1%, and the convergence time is 9.3%. Further research is recommended to be conducted for these metrics: latency, Packet Delivery Ratio (PDR), and throughput.
Kleinstlebewesen vorgestellt, das Vitalparameter erfasst und diese in einem FRAM-Speicher bis zum Auslesen abspeichert. Durch eine drahtlose RFID-/NFC-Ausleseschnittstelle kann die erfasste Körpertemperatur und der Puls der letzten Wochen ausgelesen werden. Alle Einstellungen des Messsystems können durch einen geeigneten RFID-Reader für Laptops oder durch Smartphones über die NFC-Schnittstelle geändert werden. Das vollständige Aufladen des nur 3 g leichten und 15 mm x 25 mm großen Messsystems erfolgt durch eine selbstgedruckte RFID-Reader-Antenne in Verbindung mit einem RFID-Reader und benötigt hierzu weniger als 21 Stunden. Bei vollständig aufgeladenem Energiespeicher ist ein Betrieb von 47 Tagen möglich. Dies wird durch ein speziell für das Messsystem konzipiertes Lade- und Powermanagement erreicht. Neben der Auswahl von energiesparenden Komponenten für die Hardware und deren bestmöglichen Nutzung, wurde die Software so optimiert, dass das Programm schnell und stromsparend abgearbeitet wird. Die Erweiterbarkeit und Anpassung wird durch das modulare Konzept auch in anderen Bereichen gewährleistet.
Durch eine stetige Preissteigerung der fossilen Energieträger werden auch im Bereich der mobilen Arbeitsmaschinen neben einer hohen Zuverlässig u.a. Forderungen nach steigenden Gesamtwirkungsgraden, mit der hierdurch einhergehenden Energieeffizienz, forciert. Auch bei mobilen Arbeitsmaschinen ist der häufig eingeschränkt zur Verfügung stehende Bauraum für Traktionsantriebe eine Herausforderung. Ziel dieser Veröffentlichung ist ein allgemeingültiger Vergleich verschiedener elektrischer Antriebsarten als Traktionsantrieb für mobile Arbeitsmaschinen.
Since direct current high energy shock fulguration was initially performed in the mid 1980s, ablation of cardiac arrhythmias has come to widespread use. Today the most frequently used energy source for catheter ablation is radio frequency (RF). It was the German engineer Peter Osypka who made available the HAT 100 as the first simple commercial RF ablator.
Nevertheless, in the first years of ablation, physicians were effectively working in the dark. Until today with an increasing understanding of arrhythmia mechanisms, both at the atrial and ventricular levels, this curative technology has made tremendous progress. Now, due to crucial improvement of RF ablation generators, temperature and contact force sensor catheters in combination with non-flouroscopic electroanatomical mapping technologies, computerized temperature and impedance controlled radiofrequency catheter ablation can be used to cure all types of arrhythmias including atrial and ventricular fibrillation. For the latter, cooled ablation by saline solution irrigated catheters has been developed to a widely used standard method. This procedure resulting in pulmonary vein isolation requires transseptal puncture and is technically demanding. Nevertheless, it has shown to be more effective than antiarrhythmic drug therapy.
While earliest RF ablations were performed with non-steerable catheters, today are used steerable sensor catheters without or with external and internal cooling and tips of 4mm or 8mm length. Further innovations like integration of mapping and cardiac imaging give exact information of the number of pulmonary veins and branching patterns and help to correlate electrical signals with anatomical structures.
The magnetic navigation significantly improved the success rates and safety of catheter ablation. Thus, in most cases RF catheter ablation has developed in the treatment of supraventricular arrhythmias from an alternative approach to drug therapy into the first therapeutic choice providing low complication rates.
In future, robotic navigation will further simplify procedures and reduce radiation exposure of this curative approach.
Responder-rate in cardiac resynchronization therapy (CRT) of patients in sinus rhythm (SR) or atrial fibrillation (AF) mainly depends on accurat selection, optimal position of the left ventricular electrode and individualization of hemodynamical parameters of the implanted biventricular pacing system during follow-up. High resolution esophageal left heart electrocardiography offers a quick and semi-invasive approach to the electrical activity of left atrium and left ventricle. It was used in 62 heart failure patients in sinus rhythm and 11 in atrial fibrillation after implantation of CRT systems to compare the semi-invasive interventricular conduction delay (IVCDE) with QRS width. In all of the patients, guideline decision for CRT was linked with IVCDE of about 40ms and up. From logical point of view, IVCDE provides the minimal target interval for the left ventricular electrode placement in order to exclude non-responders. Esophageal measurement of interatrial conduction intervals in VDD and DDD pacing was utilized to individualize the AV delay and to exclude adverse hemodynamic effects.
HPTLC (High Performance Thin Layer Chromatography) is a well known and versatile separation method which shows a lot of advantages and options in comparison to other separation techniques. The method is fast and inexpensive and does not need time-consuming pretreatments. Using fiber-optic elements for controlled light-guiding, the TLC-method was significantly improved: the new HPTLC-system is able to measure simultaneously at different wavelengths without destroying the plate surface or the analytes on the surface. For registration of the sample distribution on a HPTLC-plate we developed a new and sturdy diode-array HPTLC- scanner which allows registration of spectra on the TLC- plates in the range of 198 nm to 610 nm with a spectral resolution better than 1.2 nm. The spatial resolution on plate is better than 160 micrometers . In the spectral mode, the new HPTLC-scanner delivers much more information than the commonly used TLC-scanner. The measurement of 450 spectra of one separation track does not need more than three minutes. However, in the fixed wavelength mode the contour plot can be measured within 15 seconds. In this case, the signal will be summarized and averaged over a spectral range having FWHM from 10 nm to 25 nm depending on the substance under test. The new diode-array HPTLC-scanner makes various chemometric applications possible. The new method can be used easily in clinical diagnostic systems easily, e.g. for blood and uring investigations. In addition, new applications are possible. For example, the rich structured PAHs were studied. Although the separation is incomplete the 16 compounds can be quantified using suitable wavelengths.
Wireless synchronization of industrial controllers is a challenging task in environments where wired solutions are not practical. The best solutions proposed so far to solve this problem require pretty expensive and highly specialized FPGA-based devices. With this work we counter the trend by introducing a straightforward approach to synchronize a fairly cheap IEEE 802.11 integrated wireless chip (IWC) with external devices. More specifically we demonstrate how we can reprogram the software running in the 802.11 IWC of the Raspberry Pi 3B and transform the receiver input potential of the wireless transceiver into a triggering signal for an external inexpensive FPGA. Experimental results show a mean-square synchronization error of less than 496 ns, while the absolute synchronization error does not exceed 6 μs. The jitter of the output signal that we obtain after synchronizing the clock of the external device did not exceed 5.2 μs throughout the whole measurement campaign. Even though we do not score new records in term of accuracy, we do in terms of complexity, cost, and availability of the required components: all these factors make the proposed technique a very promising of the deployment of large-scale low-cost automation solutions.
Top-level staff prefers to live in urban areas with perfect social infrastructure. This is a common problem for excellent companies (“hidden champions”) in rural areas: even if they can provide the services qualified applicants appreciate for daily living, they fail to attract them because important facts are not presented sufficiently in social media or on the corporate website. This is especially true for applicants with families. The contribution of this paper is four-fold: we provide an overview of the current state of online recruiting activities of hidden champions (1). Based on this corpus, we describe the applicant service gap for company information in rural communes (2). A study on user experience (UX) identifies the applicants’ wishes and needs, focusing on a family-oriented information system on living conditions in rural areas (3). Finally, we present the results of an online survey on the value of such information systems with more than 200 participants (4).
Hintergrund: Richtung und Stärke des elektrischen Feldes (E-Feld) der biventrikulären (BV) Stimulation und elektrische interventrikuläre Desynchronisation sind bei Patienten mit Herzinsuffizienz und verbreitertem QRS Komplex von Bedeutung für den Erfolg der kardialen Resynchronisationstherapie (CRT). Das 3D Herzrhythmusmodell (HRM) ermöglicht die
Simulation von CRT und Hochfrequenz (HF) Ablation. Das Ziel der Studie besteht in der Integration von Schrittmacher- und Ablationselektroden in das HRM zur E-Feld Simulation der BV Stimulation und thermischen Feld (T-Feld) Simulation der HF Ablation von Vorhofflimmern (AF).
Methoden: Es wurden fünf multipolare linksventrikuläre (LV) Elektroden, eine epikardiale LV Elektrode, vier bipolare rechtsatriale (RA) Elektroden, zwei rechtsventrikuläre (RV) Elektroden und ein HF Ablationskatheter mit CST (Computer Simulation Technology, Darmstadt) modelliert und das HRM (Schalk et al: Clin Res Cardiol 106, Suppl 1, April 2017, P1812) um den Koronarvenensinus (CS) erweitert (HRM-CS). E-Feld Simulationen bei vorhofsynchroner BV Stimulation und bei RA Stimulation mit RV und LV Ableitung erfolgten mit den Elektroden Select Secure 3830, Capsure VDD-2 5038 und Attain OTW 4194 im HRM+CS (Fig.). F-Feld Simulationen der HF Ablation von AF bei CRT wurden mit integriertem Ablationskatheter AlCath G FullCircle (Biotronik) simuliert.
Ergebnisse: HRM-CS ermöglichte 3D E-Feld Simulationen bei vorhofsynchroner bipolarer BV Stimulation und bei bipolarer RA Stimulation mit bipolarer RV und LV Ableitung. RV und LV Stimulation erfolgten zeitgleich bei einer Amplitude von 3 V an der LV Elektrode und 1 V an der RV Elektrode mit einer Impulsbreite von jeweils 0,5 ms. Die von der BV Stimulationen erzeugten Fernpotentiale konnten von der RA Elektrode wahrgenommen werden. Das Fernpotential an der RA Elektrodenspitze betrug 32,86 mV und in 1 mm Abstand von der RA Elektrodenspitze ergab sich ein Fernpotential von 185,97 mV. HRM-CS ermöglichte 3D T-Feld Simulationen der HF Ablation von AF bei CRT. Das T-Feld bei HF Ablation des AV-Knotens wurde mit einer anliegenden Leistung von 5 W bei 420 kHz an der distalen 8 mm Ablationselektrode simuliert. Die Temperatur an der Katheterspitze betrug nach 5 s Ablationsdauer 88,66 °C, in 1 mm Abstand von der Katheterspitze im Myokard 42,17 °C und in 2 mm Abstand 37,49 °C.
Schlussfolgerungen: HRM-CS und Elektrodenmodelle ermöglichen die 3D Simulationen von E-Feldern bei vorhofsynchroner BV Stimulation, RA Stimulation mit RV und LV Wahrnehmung und von T-Feldern bei HF Ablation. E-Feld Simulationen von RA, RV und LV Stimulation und Sensing können möglicherweise zur Vorhersage von CRT Respondern genutzt werden.