Refine
Year of publication
Institute
- Fachbereich Elektrotechnik und Informationstechnik (711) (remove)
Has Fulltext
- no (711) (remove)
Language
- English (711) (remove)
Document Type
- Article (413)
- Conference Proceeding (228)
- Part of a Book (38)
- Book (23)
- Conference: Meeting Abstract (5)
- Patent (2)
- Conference Poster (1)
- Doctoral Thesis (1)
Keywords
- Enterprise Architecture (5)
- MINLP (5)
- Engineering optimization (4)
- Optimization (3)
- Powertrain (3)
- Technical Operations Research (3)
- Telecommunication (3)
- Competence Developing Games (2)
- Energy efficiency (2)
- Engineering education (2)
- Experimental validation (2)
- Gamification (2)
- Hot S-parameter (2)
- Machine Learning (2)
- Optimal Topology (2)
- Process engineering (2)
- Pump System (2)
- Robotic Process Automation (2)
- Serious Game (2)
- Ventilation System (2)
- Water (2)
- Water distribution system (2)
- autonomous driving (2)
- mathematical optimization (2)
- robotic process automation (2)
- 197m/gHg (1)
- 3-D printing (1)
- 3D object detection (1)
- Accuracy (1)
- Advanced driver assistance systems (ADAS/AD) (1)
- Agile development (1)
- Agility (1)
- Android (1)
- Angle Sensor (1)
- Anomaly detection (1)
- Artificial Intelligence (1)
- Automated driving (1)
- Automation (1)
- Automotive application (1)
- Autonomous mobile robots (1)
- Awareness (1)
- BEV (1)
- Benchmark (1)
- Bloom’s Taxonomy (1)
- Booster Stations (1)
- Buffering Capacity (1)
- Building Automation (1)
- Business Engineering (1)
- Business Process (1)
- CAV (1)
- CDG (1)
- CO2 (1)
- Carbon Dioxide (1)
- Cardiovascular Magnetic Resonance (1)
- Case Study (1)
- Case study (1)
- Chance Constraint (1)
- Change culture (1)
- Charging stations (1)
- Circuit simulation (1)
- Competence Developing Game (1)
- Computational modeling (1)
- Connected Automated Vehicle (1)
- Conpot (1)
- Control (1)
- Control engineering (1)
- Controller Parameter (1)
- Cooling system (1)
- Cryptographic protocols (1)
- Customer Orientation (1)
- DC machines (1)
- Data analysis (1)
- Data visualization (1)
- Datasets (1)
- Deep learning (1)
- Digital Age (1)
- Digital Twin Evolution (1)
- Digital transformation (1)
- Digital triage (1)
- Digital twin (1)
- Discrete Optimisation (1)
- Drinking Water Supply (1)
- E-carsharing (1)
- E-mobility (1)
- EGG (1)
- Education (1)
- Efficiency (1)
- Efficiency optimization (1)
- Electrocardiography (1)
- Electronic learning (1)
- Elicit (1)
- Energy (1)
- Energy Disaggregation (1)
- Engineering Application (1)
- Engineering optimisation (1)
- Enterprise architecture (1)
- Enterprise transformation (1)
- FPGA (1)
- Frequency Doubler (1)
- Fully connected car (1)
- Furnace (1)
- Fusion (1)
- Future Skills (1)
- GPU (1)
- Game-based learning (1)
- Gearbox (1)
- Global optimization (1)
- Gold nanoparticle (AuNP) (1)
- Graph Theory (1)
- Harmonic Radar (1)
- Heuristic algorithms (1)
- High field MRI (1)
- Home Assistant (1)
- Home Automation Platform (1)
- ICS (1)
- IP-based networks (1)
- ISO 26262 (1)
- IT security education (1)
- Image Database (1)
- Image Forensics (1)
- Image Quality Assessment (1)
- Image Quality Score (1)
- Implementation Case (1)
- Incremental Encoder (1)
- Inductive charging (1)
- Industrial optimisation (1)
- Industry 4.0 (1)
- Information and communication technology (1)
- Integrated mobility (1)
- Interactive process mining (1)
- Interdisciplinarity (1)
- Interval Time Series (1)
- Keyword analysis (1)
- LQR (1)
- Larynx position (1)
- Latin Hypercube Sampling (1)
- Leaderboard (1)
- Lean thinking (1)
- Level Control System (1)
- Li7La3Zr2O12 (1)
- LiDAR (1)
- LiGaO2 (1)
- Lidar (1)
- Literature review (1)
- Low voltage (1)
- MATLAB , MLPI , Motion control , Open Core , industrial drives , rapid control prototypin , sercos automation bus (1)
- MILP (1)
- MPC (1)
- MR safety (1)
- MRI (1)
- Machine learning (1)
- Magneto alert sensor (1)
- Malicious model (1)
- Manifolds (1)
- Map (eTOM) Process reference model Process design Telecommunications industry (1)
- Matlab (1)
- Meitner-Auger-electron (MAE) (1)
- Methodology (1)
- Minimum Risk Manoeuvre (1)
- Mixed Integer Programming (1)
- Mixed-Integer Nonlinear Optimisation (1)
- Mixed-integer nonlinear black-box optimization (1)
- Mixed-integer nonlinear problem (1)
- Mixed-integer nonlinear programming (1)
- Mixed-integer programming (1)
- Mobile Phones (1)
- Mobility management (1)
- Mode converter (1)
- Modeling (1)
- Monitoring (1)
- Mpc (1)
- Multi-criteria optimization (1)
- Multi-robot systems (1)
- NGN (1)
- Navigation (1)
- Network (1)
- Network design (1)
- Neural networks (1)
- Next Generation Network (1)
- OR 2019 (1)
- Objective data (1)
- Online services (1)
- Open Source (1)
- Operational Design Domain (1)
- Optimal Closed Loop (1)
- PPO (1)
- Paper recycling (1)
- Path-following (1)
- Performance (1)
- Personality (1)
- Piecewise Linearization (1)
- Piecewise linearization (1)
- Plasma (1)
- Plasma diagnostics (1)
- Player Types (1)
- Position Encoder (1)
- Power dissipation (1)
- Preface (1)
- Privacy-enhancing technologies (1)
- Process design (1)
- Process optimization (1)
- Process reference model (1)
- Process virtualization (1)
- Product bundling (1)
- Product family optimization (1)
- Prototype (1)
- Pumping systems (1)
- Quality control (1)
- Quantum Computing (1)
- Quantum Machine Learning (1)
- Radar (1)
- Reference Process Model (1)
- Reference modelling (1)
- Reinforcement Learning (1)
- Rescue System (1)
- Research process (1)
- Resilience (1)
- Resilience Assessment (1)
- Resilience assessment (1)
- Resilience metric graph theory (1)
- Resilient infrastructure (1)
- RoboCup (1)
- Robotic process automation (1)
- Rotary encoder (1)
- Rotational Encoder (1)
- Rotatory Inverted Pendulum (1)
- Safety of the intended functionality (SOTIF) (1)
- Safety-critical systems validation (1)
- Secure multi-party computation (1)
- Self-driving (1)
- Sensors comparison (1)
- Serious Games (1)
- Services (1)
- Similarity Theory (1)
- Smart Building (1)
- Smart factory (1)
- Society (1)
- Software (1)
- Software Robots (1)
- Software development (1)
- Software packages (1)
- Software testing (1)
- Solver Per- formance (1)
- Sound Pressure Level (1)
- Stochastic Programming (1)
- Story (1)
- Stress testing (1)
- Subject-oriented Business Process Management (1)
- Sustainability (1)
- Synchronous machines (1)
- System Design (1)
- System Design Problem (1)
- TGA (1)
- TM Forum (1)
- Tag (1)
- Targeted radionuclide therapy (TRT) (1)
- Teamwork (1)
- Technical Operation Research (1)
- Telecommunication Industry (1)
- Telecommunications Industry. (1)
- Text analytics (1)
- Text mining (1)
- Three-dimensional displays (1)
- Throughput (1)
- Time-series synchronization (1)
- Tomography (1)
- Training (1)
- Transdisciplinarity (1)
- Transfer impedance (1)
- Transformation (1)
- Transformation Project (1)
- Transformative Competencies (1)
- Transiton of Control (1)
- Transponder (1)
- Triage-app (1)
- Uktrahigh field MRI (1)
- Uncertainty (1)
- Urban areas (1)
- V2X (1)
- VOP compression (1)
- Validation (1)
- Video Game (1)
- Voice assessment (1)
- WLTP (1)
- Water Distribution (1)
- Water Supply Networks (1)
- Water Supply System (1)
- Water supply system (1)
- Wearable electronic device (1)
- Wiegand Effect (1)
- Wiegand sensor (1)
- Zero-knowledge proofs (1)
- active learning (1)
- agile (1)
- anticipation strategy (1)
- applications (1)
- artificial intelligence (1)
- automated vehicles (1)
- availability (1)
- batteries and fuel cells (1)
- body imaging at 7 T MRI (1)
- body imaging at UHF MRI (1)
- business analytics (1)
- business process automation (1)
- business simulation (1)
- commercial offthe- shelf solutions (1)
- competence developing games (1)
- connected automated vehicles (1)
- culpability (1)
- cybersecurity (1)
- decision analytics (1)
- design of technical systems (1)
- digital economy (1)
- do-it-yourself (1)
- eTOM (1)
- education (1)
- electrospinning (1)
- embedded hardware (1)
- energy efficiency (1)
- energy transfer (1)
- enhanced Telecom Operations Map (eTOM) (1)
- experimental evaluation (1)
- fault detection (1)
- fibers (1)
- ga-doping (1)
- garnet solid electrolyte (1)
- genetic algorithm (1)
- global optimization (1)
- harmonic radar (1)
- harmonic radar tags (1)
- heating system (1)
- honeynet (1)
- honeypot (1)
- ignition (1)
- information systems (1)
- integrated transmit coil arrays (1)
- irradiation (1)
- lab work (1)
- learning theories (1)
- legal obligations (1)
- liability (1)
- management (1)
- metrological characterization (1)
- microplasma (1)
- microwave (MW) plasma (1)
- microwave measurements (1)
- mixed-integer linear programming (1)
- model-predictive control (1)
- motivation theories (1)
- next generation network (1)
- nonlinear VNA measurements (1)
- optimization (1)
- passive inter-modulation (1)
- plasma jet (1)
- porous materials (1)
- power integrity (1)
- product bundling (1)
- product liability (1)
- professional skills (1)
- programming (1)
- remote sensing (1)
- requirements (1)
- research framework (1)
- resilience (1)
- sensor networks (1)
- signal integrity (1)
- slum classification (1)
- software engineering (1)
- software evaluation (1)
- software selection (1)
- solid-state battery (1)
- stochastic optimization (1)
- sustainability (1)
- system optimization (1)
- system synthesis (1)
- systematic literature review (1)
- tablet game (1)
- technical operations research (1)
- technology (1)
- telecommunication (1)
- thermal dose (1)
- tissue temperature (1)
- transmit antenna arrays (1)
- water supply design (1)
- water supply system (1)
Due to the high number of customer contacts, fault clearances, installations, and product provisioning per year, the automation level of operational processes has a significant impact on financial results, quality, and customer experience. Therefore, the telecommunications operator Deutsche Telekom (DT) has defined a digital strategy with the objectives of zero complexity and zero complaint, one touch, agility in service, and disruptive thinking. In this context, Robotic Process Automation (RPA) was identified as an enabling technology to formulate and realize DT’s digital strategy through automation of rule-based, routine, and predictable tasks in combination with structured and stable data.
Compared to peripheral pain, trigeminal pain elicits higher levels of fear, which is assumed to enhance the interruptive effects of pain on concomitant cognitive processes. In this fMRI study we examined the behavioral and neural effects of trigeminal (forehead) and peripheral (hand) pain on visual processing and memory encoding. Cerebral activity was measured in 23 healthy subjects performing a visual categorization task that was immediately followed by a surprise recognition task. During the categorization task subjects received concomitant noxious electrical stimulation on the forehead or hand. Our data show that fear ratings were significantly higher for trigeminal pain. Categorization and recognition performance did not differ between pictures that were presented with trigeminal and peripheral pain. However, object categorization in the presence of trigeminal pain was associated with stronger activity in task-relevant visual areas (lateral occipital complex, LOC), memory encoding areas (hippocampus and parahippocampus) and areas implicated in emotional processing (amygdala) compared to peripheral pain. Further, individual differences in neural activation between the trigeminal and the peripheral condition were positively related to differences in fear ratings between both conditions. Functional connectivity between amygdala and LOC was increased during trigeminal compared to peripheral painful stimulation. Fear-driven compensatory resource activation seems to be enhanced for trigeminal stimuli, presumably due to their exceptional biological relevance.
Short term effects of magnetic resonance imaging on excitability of the motor cortex at 1.5T and 7T
(2010)
Rationale and Objectives
The increasing spread of high-field and ultra-high-field magnetic resonance imaging (MRI) scanners has encouraged new discussion of the safety aspects of MRI. Few studies have been published on possible cognitive effects of MRI examinations. The aim of this study was to examine whether changes are measurable after MRI examinations at 1.5 and 7 T by means of transcranial magnetic stimulation (TMS).
Materials and Methods
TMS was performed in 12 healthy, right-handed male volunteers. First the individual motor threshold was specified, and then the cortical silent period (SP) was measured. Subsequently, the volunteers were exposed to the 1.5-T MRI scanner for 63 minutes using standard sequences. The MRI examination was immediately followed by another TMS session. Fifteen minutes later, TMS was repeated. Four weeks later, the complete setting was repeated using a 7-T scanner. Control conditions included lying in the 1.5-T scanner for 63 minutes without scanning and lying in a separate room for 63 minutes. TMS was performed in the same way in each case. For statistical analysis, Wilcoxon's rank test was performed.
Results
Immediately after MRI exposure, the SP was highly significantly prolonged in all 12 subjects at 1.5 and 7 T. The motor threshold was significantly increased. Fifteen minutes after the examination, the measured value tended toward normal again. Control conditions revealed no significant differences.
Conclusion
MRI examinations lead to a transient and highly significant alteration in cortical excitability. This effect does not seem to depend on the strength of the static magnetic field.
Purpose
To assess potential cognitive deficits under the influence of static magnetic fields at various field strengths some studies already exist. These studies were not focused on attention as the most vulnerable cognitive function. Additionally, mostly no magnetic resonance imaging (MRI) sequences were performed.
Materials and Methods
In all, 25 right-handed men were enrolled in this study. All subjects underwent one MRI examination of 63 minutes at 1.5 T and one at 7 T within an interval of 10 to 30 days. The order of the examinations was randomized. Subjects were referred to six standardized neuropsychological tests strictly focused on attention immediately before and after each MRI examination. Differences in neuropsychological variables between the timepoints before and after each MRI examination were assessed and P-values were calculated
Results
Only six subtests revealed significant differences between pre- and post-MRI. In these tests the subjects achieved better results in post-MRI testing than in pre-MRI testing (P = 0.013–0.032). The other tests revealed no significant results.
Conclusion
The improvement in post-MRI testing is only explicable as a result of learning effects. MRI examinations, even in ultrahigh-field scanners, do not seem to have any persisting influence on the attention networks of human cognition immediately after exposure.
Reasoning with Qualitative Positional Information for Domestic Domains in the Situation Calculus
(2011)
In this paper we present CAESAR, an intelligent domestic service robot. In domestic settings for service robots complex tasks have to be accomplished. Those tasks benefit from deliberation, from robust action execution and from flexible methods for human–robot interaction that account for qualitative notions used in natural language as well as human fallibility. Our robot CAESAR deploys AI techniques on several levels of its system architecture. On the low-level side, system modules for localization or navigation make, for instance, use of path-planning methods, heuristic search, and Bayesian filters. For face recognition and human–machine interaction, random trees and well-known methods from natural language processing are deployed. For deliberation, we use the robot programming and plan language READYLOG, which was developed for the high-level control of agents and robots; it allows combining programming the behaviour using planning to find a course of action. READYLOG is a variant of the robot programming language Golog. We extended READYLOG to be able to cope with qualitative notions of space frequently used by humans, such as “near” and “far”. This facilitates human–robot interaction by bridging the gap between human natural language and the numerical values needed by the robot. Further, we use READYLOG to increase the flexible interpretation of human commands with decision-theoretic planning. We give an overview of the different methods deployed in CAESAR and show the applicability of a system equipped with these AI techniques in domestic service robotics
In this paper we present an extension of the action language Golog that allows for using fuzzy notions in non-deterministic argument choices and the reward function in decision-theoretic planning. Often, in decision-theoretic planning, it is cumbersome to specify the set of values to pick from in the non-deterministic-choice-of-argument statement. Also, even for domain experts, it is not always easy to specify a reward function. Instead of providing a finite domain for values in the non-deterministic-choice-of-argument statement in Golog, we now allow for stating the argument domain by simply providing a formula over linguistic terms and fuzzy uents. In Golog’s forward-search DT planning algorithm, these formulas are evaluated in order to find the agent’s optimal policy. We illustrate this in the Diner Domain where the agent needs to calculate the optimal serving order.
In this work, we report on our attempt to design and implement an early introduction to basic robotics principles for children at kindergarten age. One of the main challenges of this effort is to explain complex robotics contents in a way that pre-school children could follow the basic principles and ideas using examples from their world of experience. What sets apart our effort from other work is that part of the lecturing is actually done by a robot itself and that a quiz at the end of the lesson is done using robots as well. The humanoid robot Pepper from Softbank, which is a great platform for human–robot interaction experiments, was used to present a lecture on robotics by reading out the contents to the children making use of its speech synthesis capability. A quiz in a Runaround-game-show style after the lecture activated the children to recap the contents they acquired about how mobile robots work in principle. In this quiz, two LEGO Mindstorm EV3 robots were used to implement a strongly interactive scenario. Besides the thrill of being exposed to a mobile robot that would also react to the children, they were very excited and at the same time very concentrated. We got very positive feedback from the children as well as from their educators. To the best of our knowledge, this is one of only few attempts to use a robot like Pepper not as a tele-teaching tool, but as the teacher itself in order to engage pre-school children with complex robotics contents.
Design and Development of a Novel Self-Igniting Microwave Plasma Jet for Industrial Applications
(2019)
The Inverted Rotary Pendulum: Facilitating Practical Teaching in Advanced Control Engineering
(2024)
This paper outlines a practical approach to teach control engineering principles, with an inverted rotary pendulum, serving as an illustrative example. It shows how the pendulum is embedded in an advanced course of control engineering. This approach is incorporated into a flipped-classroom concept, as well as classical teaching concepts, offering students practical experience in control engineering. In addition, the design of the pendulum is shown, using a Raspberry Pi as the target platform for Matlab Simulink. This pendulum can be used in the classroom to evaluate the controller design mentioned above. It is analysed if the use of the pendulum generates a deeper understanding of the learning contents.
Game-based learning is a promising approach to anti-phishing education, as it fosters motivation and can help reduce the perceived difficulty of the educational material. Over the years, several prototypes for game-based applications have been proposed, that follow different approaches in content selection, presentation, and game mechanics. In this paper, a literature and product review of existing learning games is presented. Based on research papers and accessible applications, an in-depth analysis was conducted, encompassing target groups, educational contexts, learning goals based on Bloom’s Revised Taxonomy, and learning content. As a result of this review, we created the publications on games (POG) data set for the domain of anti-phishing education. While there are games that can convey factual and conceptual knowledge, we find that most games are either unavailable, fail to convey procedural knowledge or lack technical depth. Thus, we identify potential areas of improvement for games suitable for end-users in informal learning contexts.
Information Channels
(2000)
Production and distribution of personalized information services employing mass customization
(2003)
The initial idea of Robotic Process Automation (RPA) is the automation of business processes through a simple emulation of user input and output by software robots. Hence, it can be assumed that no changes of the used software systems and existing Enterprise Architecture (EA) is
required. In this short, practical paper we discuss this assumption based on a real-life implementation project. We show that a successful RPA implementation might require architectural work during analysis, implementation, and migration. As practical paper we focus on exemplary lessons-learned and new questions related to RPA and EA.
In this paper we report on an architecture for a self-driving car that is based on ROS2. Self-driving cars have to take decisions based on their sensory input in real-time, providing high reliability with a strong demand in functional safety. In principle, self-driving cars are robots. However, typical robot software, in general, and the previous version of the Robot Operating System (ROS), in particular, does not always meet these requirements. With the successor ROS2 the situation has changed and it might be considered as a solution for automated and autonomous driving. Existing robotic software based on ROS was not ready for safety critical applications like self-driving cars. We propose an architecture for using ROS2 for a self-driving car that enables safe and reliable real-time behaviour, but keeping the advantages of ROS such as a distributed architecture and standardised message types. First experiments with an automated real passenger car at lower and higher speed-levels show that our approach seems feasible for autonomous driving under the necessary real-time conditions.
Rugged terrain robot designs are important for field robotics missions. A number of commercial platforms are available, however, at an impressive price. In this paper, we describe the hardware and software component of a low-cost wheeled rugged-terrain robot. The robot is based on an electric children quad bike and is modified to be driven by wire. In terms of climbing properties, operation time and payload it can compete with some of the commercially available platforms, but at a far lower price.
Finding a good system topology with more than a handful of components is a
highly non-trivial task. The system needs to be able to fulfil all expected load cases, but at the
same time the components should interact in an energy-efficient way. An example for a system
design problem is the layout of the drinking water supply of a residential building. It may be
reasonable to choose a design of spatially distributed pumps which are connected by pipes in at
least two dimensions. This leads to a large variety of possible system topologies. To solve such
problems in a reasonable time frame, the nonlinear technical characteristics must be modelled
as simple as possible, while still achieving a sufficiently good representation of reality. The
aim of this paper is to compare the speed and reliability of a selection of leading mathematical
programming solvers on a set of varying model formulations. This gives us empirical evidence
on what combinations of model formulations and solver packages are the means of choice with the current state of the art.
The UN sets the goal to ensure access to water and sanitation for all people by 2030. To address this goal, we present a multidisciplinary approach for designing water supply networks for slums in large cities by applying mathematical optimization. The problem is modeled as a mixed-integer linear problem (MILP) aiming to find a network describing the optimal supply infrastructure. To illustrate the approach, we apply it on a small slum cluster in Dhaka, Bangladesh.
Ensuring access to water and sanitation for all is Goal No. 6 of the 17 UN Sustainability Development Goals to transform our world. As one step towards this goal, we present an approach that leverages remote sensing data to plan optimal water supply networks for informal urban settlements. The concept focuses on slums within large urban areas, which are often characterized by a lack of an appropriate water supply. We apply methods of mathematical optimization aiming to find a network describing the optimal supply infrastructure. Hereby, we choose between different decentral and central approaches combining supply by motorized vehicles with supply by pipe systems. For the purposes of illustration, we apply the approach to two small slum clusters in Dhaka and Dar es Salaam. We show our optimization results, which represent the lowest cost water supply systems possible. Additionally, we compare the optimal solutions of the two clusters (also for varying input parameters, such as population densities and slum size development over time) and describe how the result of the optimization depends on the entered remote sensing data.
The increasing complexity of Advanced Driver Assistance Systems (ADAS) presents a challenging task to validate safe and reliable performance of these systems under varied conditions. The test and validation of ADAS/AD with real test drives, although important, involves huge costs and time. Simulation tools provide an alternative with the added advantage of reproducibility but often use ideal sensors, which do not reflect real sensor output accurately. This paper presents a new validation methodology using fault injection, as recommended by the ISO 26262 standard, to test software and system robustness. In our work, we investigated and developed a tool capable of inserting faults at different software and system levels to verify its robustness. The scope of this paper is to cover the fault injection test for the Visteon’s DriveCore™ system, a centralized domain controller for Autonomous driving which is sensor agnostic and SoC agnostic. With this new approach, the validation of safety monitoring functionality and its behavior can be tested using real-world data instead of synthetic data from simulation tools resulting in having better confidence in system performance before proceeding with in-vehicle testing.
Information and communication technology for integrated mobility concepts such as E-carsharing
(2015)
During the past decade attitude towards sharing things has changed extremely. Not just personal data is shared (e.g. in social networks) but also mobility. Together with the increased ecological awareness of the recent years, new mobility concepts have evolved. E-carsharing has become a symbol for these changes of attitude. The management of a shared car fleet, the energy management of electric mobility and the management of various carsharing users with individual likes and dislikes are just some of the major challenges of e-carsharing. Weaving it into integrated mobility concepts, this raises complexity even further. These challenges can only be overcome by an appropriate amount of well-shaped information available at the right place and time. In order to gather, process and share the required information, fleet cars have to be equipped with modern information and communication technology (ICT) and become so-called fully connected cars. Ensuring the usability of these ICT systems is another challenge that is often neglected, even though it is usability that makes carsharing comfortable, attractive and supports users’ new attitudes. By means of an integrated and consistent concept for human-machine interaction (HMI), the usability of such systems can be raised tremendously.
The conference center darmstadtium in Darmstadt is a prominent example of energy efficient buildings. Its heating system consists of different source and consumer circuits connected by a Zortström reservoir. Our goal was to reduce the energy costs of the system as much as possible. Therefore, we analyzed its supply circuits. The first step towards optimization is a complete examination of the system: 1) Compilation of an object list for the system, 2) collection of the characteristic curves of the components, and 3) measurement of the load profiles of the heat and volume-flow demand. Instead of modifying the system manually and testing the solution by simulation, the second step was the creation of a global optimization program. The objective was to minimize the total energy costs for one year. We compare two different topologies and show opportunities for significant savings.
In this paper, the multicarrier physical layers of WiMAX are evaluated in the context of airport data links. The orthogonal frequency-division multiplexing (OFDM) and orthogonal frequency-division multiple-access (OFDMA) cases are applied to the forward link (FL) and reverse link (RL), respectively. The performance of the so called parking and taxi scenarios is presented for airport communications in C-band. Numerical results show that the proposed scheme brings good performance for both the FL and the RL. For the OFDMA case a structure changing called double-tile is also proposed to improve the system performance.
Harmful effects of electromagnetic fields (EMF) on cognitive and behavioural features of humans and rodents have been controversially discussed and raised persistent concern about adverse effects of EMF on general brain functions. In the present study we applied radio-frequency (RF) signals of the Universal Mobile Telecommunications System (UMTS) to full brain exposed male Wistar rats in order to elaborate putative influences on stress hormone release (corticosteron; CORT and adrenocorticotropic hormone; ACTH) and on hippocampal derived synaptic long-term plasticity (LTP) and depression (LTD) as electrophysiological hallmarks for memory storage and memory consolidation. Exposure was computer controlled providing blind conditions. Nominal brain-averaged specific absorption rates (SAR) as a measure of applied mass-related dissipated RF power were 0, 2, and 10 W/kg over a period of 120 min. Comparison of cage exposed animals revealed, regardless of EMF exposure, significantly increased CORT and ACTH levels which corresponded with generally decreased field potential slopes and amplitudes in hippocampal LTP and LTD. Animals following SAR exposure of 2 W/kg (averaged over the whole brain of 2.3 g tissue mass) did not differ from the sham-exposed group in LTP and LTD experiments. In contrast, a significant reduction in LTP and LTD was observed at the high power rate of SAR (10 W/kg). The results demonstrate that a rate of 2 W/kg displays no adverse impact on LTP and LTD, while 10 W/kg leads to significant effects on the electrophysiological parameters, which can be clearly distinguished from the stress derived background. Our findings suggest that UMTS exposure with SAR in the range of 2 W/kg is not harmful to critical markers for memory storage and memory consolidation, however, an influence of UMTS at high energy absorption rates (10 W/kg) cannot be excluded.
Many biped robots deploy a form of gait that follows the zero moment point (ZMP) approach, that is, the robot is in a stable position at any point in time. This requires the robot to be fully actuated. While very stable, the draw-backs of this approach are a fairly slow gait and high energy consumption. An alternative approach is the so-called passive-dynamic walking, where the gait makes use of the inertia and dynamic stability of the robot. In this paper we describe our ongoing work of combining the principles of passive-dynamic walking on the fully-actuated biped robot Nao, which is also deployed for robotic soccer applications. We present a simple controller that allows the robot to stably rock sidewards, showing a closed limit-cycle. We discuss first results of superimposing a forward motion on the sidewards motion. Based on this we expect to endow the Nao with a fast, robust, and stable passive-dynamic walk on the fully-actuated Nao in the future.
This chapter describes three general strategies to master uncertainty in technical systems: robustness, flexibility and resilience. It builds on the previous chapters about methods to analyse and identify uncertainty and may rely on the availability of technologies for particular systems, such as active components. Robustness aims for the design of technical systems that are insensitive to anticipated uncertainties. Flexibility increases the ability of a system to work under different situations. Resilience extends this characteristic by requiring a given minimal functional performance, even after disturbances or failure of system components, and it may incorporate recovery. The three strategies are described and discussed in turn. Moreover, they are demonstrated on specific technical systems.
This paper covers the use of the magnetic Wiegand effect to design an innovative incremental encoder. First, a theoretical design is given, followed by an estimation of the achievable accuracy and an optimization in open-loop operation.
Finally, a successful experimental verification is presented. For this purpose, a permanent magnet synchronous machine is controlled in a field-oriented manner, using the angle information of the prototype.
As the field strength and, therefore, the operational frequency in MRI is increased, the wavelength approaches the size of the human head/body, resulting in wave effects, which cause signal decreases and dropouts. Several multichannel approaches have been proposed to try to tackle these problems, including RF shimming, where each element in an array is driven by its own amplifier and modulated with a certain (constant) amplitude and phase relative to the other elements, and Transmit SENSE, where spatially tailored RF pulses are used. In this article, a relatively inexpensive and easy to use imaging scheme for 7 Tesla imaging is proposed to mitigate signal voids due to B1 field inhomogeneity. Two time-interleaved images are acquired using a different excitation mode for each. By forming virtual receive elements, both images are reconstructed together using GRAPPA to achieve a more homogeneous image, with only small SNR and SAR penalty in head and body imaging at 7 Tesla.
Purpose
To calculate local specific absorption rate (SAR) correctly, both the amplitude and phase of the signal in each transmit channel have to be known. In this work, we propose a method to derive a conservative upper bound for the local SAR, with a reasonable safety margin without knowledge of the transmit phases of the channels.
Methods
The proposed method uses virtual observation points (VOPs). Correction factors are calculated for each set of VOPs that prevent underestimation of local SAR when the VOPs are applied with the correct amplitudes but fixed phases.
Results
The proposed method proved to be superior to the worst-case calculation based on the maximum eigenvalue of the VOPs. The mean overestimation for six coil setups could be reduced, whereas no underestimation of the maximum local SAR occurred. In the best investigated case, the overestimation could be reduced from a factor of 3.3 to a factor of 1.7.
Conclusion
The upper bound for the local SAR calculated with the proposed method allows a fast estimation of the local SAR based on power measurements in the transmit channels and facilitates SAR monitoring in systems that do not have the capability to monitor transmit phases
Objective
In local SAR compression algorithms, the overestimation is generally not linearly dependent on actual local SAR. This can lead to large relative overestimation at low actual SAR values, unnecessarily constraining transmit array performance.
Method
Two strategies are proposed to reduce maximum relative overestimation for a given number of VOPs. The first strategy uses an overestimation matrix that roughly approximates actual local SAR; the second strategy uses a small set of pre-calculated VOPs as the overestimation term for the compression.
Result
Comparison with a previous method shows that for a given maximum relative overestimation the number of VOPs can be reduced by around 20% at the cost of a higher absolute overestimation at high actual local SAR values.
Conclusion
The proposed strategies outperform a previously published strategy and can improve the SAR compression where maximum relative overestimation constrains the performance of parallel transmission.
Purpose:
At 1.5 T, real-time MRI of joint movement has been shown to be feasible. However, 7 T, provides higher SNR and thus an improved potential for parallel imaging acceleration. The purpose of this work was to build an open, U-shaped eight-channel transmit/receive microstrip coil for 7 T MRI to enable high-resolution and real-time imaging of the moving ankle joint.
Methods:
A U-shaped eight-channel transmit/receive array for the human ankle was built.urn:x-wiley:00942405:mp3399:equation:mp3399-math-0001-parameters and urn:x-wiley:00942405:mp3399:equation:mp3399-math-0002-factor were measured. SAR calculations of different ankle postures were performed to ensure patient safety. Inhomogeneities in the transmit field consequent to the open design were compensated for by the use of static RF shimming. High-resolution and real-time imaging was performed in human volunteers.
Results:
The presented array showed good performance with regard to patient comfort and image quality. High acceleration factors of up to 4 are feasible without visible acceleration artifacts. Reasonable image homogeneity was achieved with RF shimming.
Conclusions:
Open, noncylindrical designs for transmit/receive coils are practical at 7 T and real-time imaging of the moving joint is feasible with the presented coil design.
s the magnetic field strength and therefore the operational frequency in MRI are increased, the radiofrequency wavelength approaches the size of the human head/body, resulting in wave effects which cause signal decreases and dropouts. Especially, whole-body imaging at 7 T and higher is therefore challenging. Recently, an acquisition scheme called time-interleaved acquisition of modes has been proposed to tackle the inhomogeneity problems in high-field MRI. The basic premise is to excite two (or more) different Burn:x-wiley:07403194:media:MRM23081:tex2gif-stack-1 modes using static radiofrequency shimming in an interleaved acquisition, where the complementary radiofrequency patterns of the two modes can be exploited to improve overall signal homogeneity. In this work, the impact of time-interleaved acquisition of mode on image contrast as well as on time-averaged specific absorption rate is addressed in detail. Time-interleaved acquisition of mode is superior in Burn:x-wiley:07403194:media:MRM23081:tex2gif-stack-2 homogeneity compared with conventional radiofrequency shimming while being highly specific absorption rate efficient. Time-interleaved acquisition of modes can enable almost homogeneous high-field imaging throughout the entire field of view in PD, T2, and T2*-weighted imaging and, if a specified homogeneity criterion is met, in T1-weighted imaging as well.