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Because of its minor environmental impact, electricity generation using wind power is getting remarkable. The further growth of the wind industry depends on technological solutions to the challenges in production and construction of the turbines. Wind turbine tower vibrations, which limit power generation efficiency and cause fatigue problems with high maintenance costs, count as one of the main structural difficulties in the wind energy sector. To mitigate tower vibrations auxiliary measures are necessary. The effectiveness of tuned mass damper is verified by means of a numeric study on a 5 MW onshore reference wind turbine. Hereby, also seismic-induced vibrations and soil–structure interaction are considered. Acquired results show that tuned mass damper can effectively reduce resonant tower vibrations and improve the fatigue life of wind turbines. This chapter is also concerned with tuned liquid column damper and a semiactive application of it. Due to its geometric versatility and low prime costs, tuned liquid column dampers are a good alternative to other damping measures, in particular for slender structures like wind turbines.
Hydraulic modeling is the classical approach to investigate and describe complex fluid motion. Many empirical formulas in the literature used for the hydraulic design of river training measures and structures have been developed using experimental data from the laboratory. Although computer capacities have increased to a high level which allows to run complex numerical simulations on standard workstation nowadays, non-standard design of structures may still raise the need to perform physical model investigations. These investigations deliver insight into details of flow patterns and the effect of varying boundary conditions. Data from hydraulic model tests may be used for calibration of numerical models as well. As the field of hydraulic modeling is very complex, this chapter intends to give a short overview on capacities and limits of hydraulic modeling in regard to river flows and hydraulic structures only. The reader shall get a first idea of modeling principles and basic considerations. More detailed information can be found in the references.
Lately there has been an increasing concern about uranium toxicity in some districts of Punjab State located in the North Western part of India after the publication of a report (Blaurock-Busch et al. 2010) which showed that the concentration of uranium in hair and urine of children suffering from physical deformities, neurological and mental disorder from Malwa region (Fig. 1) of Punjab State was manifold higher than the reference ranges. A train which connects the affected region with the nearby city of Bikaner which has a Cancer Hospital has been nicknamed as Cancer Express due to the frenzy generated on account of uranium related toxicity.
We present a robotic tool that autonomously follows a conversation to enable remote presence in video conferencing. When humans participate in a meeting with the help of video conferencing tools, it is crucial that they are able to follow the conversation both with acoustic and visual input. To this end, we design and implement a video conferencing tool robot that uses binaural sound source localization as its main source to autonomously orient towards the currently talking speaker. To increase robustness of the acoustic cue against noise we supplement the sound localization with a source detection stage. Also, we include a simple onset detector to retain fast response times. Since we only use two microphones, we are confronted with ambiguities on whether a source is in front or behind the device. We resolve these ambiguities with the help of face detection and additional moves. We tailor the system to our target scenarios in experiments with a four minute scripted conversation. In these experiments we evaluate the influence of different system settings on the responsiveness and accuracy of the device.
The production and assembly of customized products increases the demand for flexible automation systems. One approach is to remove the safety fences that separate human and industrial robot to combine their skills. This collaboration possesses a certain risk for the human co-worker, leading to numerous safety concepts to protect him. The human needs to be monitored and tracked by a safety system using different sensors. The proposed system consists of a RGBD camera for surveillance of the common working area, an array of optical distance sensors to compensate shadowing effects of the RGBD camera and a laser range finder to detect the co-worker when approaching the work cell. The software for collision detection, path planning, robot control and predicting the behaviour of the co-worker is based on the Robot Operating System (ROS). A first prototype of the work cell shows that with advanced algorithms from the field of mobile robotics a very flexible safety concept can be realized: the robot not simply stops its movement when detecting a collision, but plans and executes an alternative path around the obstacle.
Various models have been proposed for the prediction of the necessary support pressure at the face of a shallow tunnel. To assess their quality, the collapse of a tunnel face was modelled with small-scale model tests at single gravity. The development of the failure mechanism and the support force at the face in dry sand were investigated. The observed displacement patterns show a negligible influence of overburden on the extent and evolution of the failure zone. The latter is significantly influenced, though, by the initial density of the sand: in dense sand a chimney-wedge-type collapse mechanism developed, which propagated towards the soil surface. Initially, loose sand did not show any discrete collapse mechanism. The necessary support force was neither influenced by the overburden nor the initial density. A comparison with quantitative predictions by several theoretical models showed that the measured necessary support pressure is overestimated by most of the models. Those by Vermeer/Ruse and Léca/Dormieux showed the best agreement to the measurements.
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.
Thermal management in E-carsharing vehicles - preconditioning concepts of passenger compartments
(2015)
The issue of thermal management in electric vehicles includes the topics of drivetrain cooling and heating, interior temperature, vehicle body conditioning and safety. In addition to the need to ensure optimal thermal operating conditions of the drivetrain components (drive motor, battery and electrical components), thermal comfort must be provided for the passengers. Thermal comfort is defined as the feeling which expresses the satisfaction of the passengers with the ambient conditions in the compartment. The influencing factors on thermal comfort are the temperature and humidity as well as the speed of the indoor air and the clothing and the activity of the passengers, in addition to the thermal radiation and the temperatures of the interior surfaces. The generation and the maintenance of free visibility (ice- and moisture-free windows) count just as important as on-demand heating and cooling of the entire vehicle. A Carsharing climate concept of the innovative ec2go vehicle stipulates and allows for only seating areas used by passengers to be thermally conditioned in a close-to-body manner. To enable this, a particular feature has been added to the preconditioning of the Carsharing electric vehicle during the electric charging phase at the parking station.
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.
For a wide acceptance of E-Mobility, a well-developed charging infrastructure is needed. Conductive charging stations, which are today’s state of the art, are of limited suitability for urbanised areas, since they cause a significant diversification in townscape. Furthermore, they might be destroyed by vandalism. Besides for those urbanistic reasons, inductive charging stations are a much more comfortable alternative, especially in urbanised areas. The usage of conductive charging stations requires more or less bulky charging cables. The handling of those standardised charging cables, especially during poor weather conditions, might cause inconvenience, such as dirty clothing etc. Wireless charging does not require visible and vandalism vulnerable charge sticks. No wired connection between charging station and vehicle is needed, which enable the placement below the surface of parking spaces or other points of interest. Inductive charging seems to be the optimal alternative for E-Mobility, as a high power transfer can be realised with a manageable technical and financial effort. For a well-accepted and working public charging infrastructure in urbanised areas it is essential that the infrastructure fits the vehicles’ needs. Hence, a well-adjusted standardisation of the charging infrastructure is essential. This is carried out by several IEC (International Electrotechnical Commission) and national standardisation committees. To ensure an optimised technical solution for future’s inductive charging infrastructures, several field tests had been carried out and are planned in near future.
In diesem Artikel werden zunächst einleitend der Gasmarkt Deutschland und der sich daraus ergebende Speicherbedarf skizziert. Folgend wird auf verschiedene Speichernutzen aus betriebswirtschaftlicher Perspektive eingegangen und die in diesem Artikel vorgestellten Bewertungsverfahren einleitend beschrieben. In diesem Artikel werden stochastische Optimierungsmethoden aufgegriffen, die sowohl eine Bewertung der Speicher gegenüber einem Spotpreis, als auch gegenüber einer gesamten Forwardcurve ermöglichen. Hierzu werden zunächst Modelle zur Beschreibung der Marktpreise vorgestellt und anhand empirischer Daten kalibriert. Dann wird eine beispielhafte Speicherscheibe zunächst auf Basis der LeastSquareMonteCarloTechnik gegenüber dem stochastischen mehrfaktoriellen Spotpreismodell bewertet. Hieran schließt sich die Vorstellung der Bewertung sowie des Hedgings gegenüber der Forwardcurve an. Abschließend erfolgt eine vergleichende Gegenüberstellung beider Verfahren.
Für die Erstellung von Maschinenbelegungsplanen wurden im Operations Research aufwendige Optimierungsverfahren konzipiert und entsprechende Programme entwickelt. Maschinenbelegungsprobleme sind klassische Vertreter der Klasse der np-vollständigen Probleme, also sichere Kandidaten für kombinatorische Explosion der Lösungsalternativen. Deshalb ist der Einsatz konventioneller Planungssysteme wegen der hohen Rechneranforderungen der gängigen Verfahren an die Hardware oft nicht praktikabel.
Bussysteme
(2006)
RGB-D sensors such as the Microsoft Kinect or the Asus Xtion are inexpensive 3D sensors. A depth image is computed by calculating the distortion of a known infrared light (IR) pattern which is projected into the scene. While these sensors are great devices they have some limitations. The distance they can measure is limited and they suffer from reflection problems on transparent, shiny, or very matte and absorbing objects. If more than one RGB-D camera is used the IR patterns interfere with each other. This results in a massive loss of depth information. In this paper, we present a simple and powerful method to overcome these problems. We propose a stereo RGB-D camera system which uses the pros of RGB-D cameras and combine them with the pros of stereo camera systems. The idea is to utilize the IR images of each two sensors as a stereo pair to generate a depth map. The IR patterns emitted by IR projectors are exploited here to enhance the dense stereo matching even if the observed objects or surfaces are texture-less or transparent. The resulting disparity map is then fused with the depth map offered by the RGB-D sensor to fill the regions and the holes that appear because of interference, or due to transparent or reflective objects. Our results show that the density of depth information is increased especially for transparent, shiny or matte objects.
This paper presents a numerical procedure for reliability analysis of thin plates and shells with respect to plastic collapse or to inadaptation. The procedure involves a deterministic shakedown analysis for each probabilistic iteration, which is based on the upper bound approach and the use of the exact Ilyushin yield surface. Probabilistic shakedown analysis deals with uncertainties originated from the loads, material strength and thickness of the shell. Based on a direct definition of the limit state function, the calculation of the failure probability may be efficiently solved by using the First and Second Order Reliability Methods (FORM and SORM). The problem of reliability of structural systems (series systems) is handled by the application of a special technique which permits to find all the design points corresponding to all the failure modes. Studies show, in this case, that it improves considerably the FORM and SORM results.
Expeditious building of ring-porous earlywood vessel chronologies without loosing signal information
(2009)
• Most of the edible forest mushrooms are mycorrhizal and depend on carbohydrates produced by the associated trees. Fruiting patterns of these fungi are not yet fully understood since climatic factors alone do not completely explain mushroom occurrence.
• The objective of this study was to retrospectively find out if changing tree growth following an increment thinning has influenced the diversity patterns and productivity of associated forest mushrooms in the fungus reserve La Chanéaz, Switzerland.
• The results reveal a clear temporal relationship between the thinning, the growth reaction of trees and the reaction of the fungal community, especially for the ectomycorrhizal species. The tree-ring width of the formerly suppressed beech trees and the fruit body number increased after thinning, leading to a significantly positive correlation between fruit body numbers and tree-ring width.
• Fruit body production was influenced by previous annual tree growth, the best accordance was found between fruit body production and the tree-ring width two years previously.
• The results support the hypothesis that ectomycorrhizal fruit body production must be linked with the growth of the associated host trees. Moreover, the findings indicate the importance of including mycorrhizal fungi as important players when discussing a tree as a carbon source or sink.
For the sterilisation of aseptic food packages it is taken advantage of the microbicidal properties of hydrogen peroxide (H2O2). Especially, when applied in vapour phase, it has shown high potential of microbial inactivation. In addition, it offers a high environmental compatibility compared to other chemical sterilisation agents, as it decomposes into oxygen and water, respectively. Due to a lack in sensory detection possibilities, a continuous monitoring of the H2O2 concentration was recently not available. Instead, the sterilisation efficacy is validated using microbiological tests. However, progresses in the development of calorimetric gas sensors during the last 7 years have made it possible to monitor the H2O2 concentration during operation. This chapter deals with the fundamentals of calorimetric gas sensing with special focus on the detection of gaseous hydrogen peroxide. A sensor principle based on a calorimetric differential set-up is described. Special emphasis is given to the sensor design with respect to the operational requirements under field conditions. The state-of-the-art regarding a sensor set-up for the on-line monitoring and secondly, a miniaturised sensor for in-line monitoring are summarised. Furthermore, alternative detection methods and a novel multi-sensor system for the characterisation of aseptic sterilisation processes are described.
Successful bone sawing requires a high level of skill and experience, which could be gained by the use of Virtual Reality-based simulators. A key aspect of these medical simulators is realistic force feedback. The aim of this paper is to model the bone sawing process in order to develop a valid training simulator for the bilateral sagittal split osteotomy, the most often applied corrective surgery in case of a malposition of the mandible. Bone samples from a human cadaveric mandible were tested using a designed experimental system. Image processing and statistical analysis were used for the selection of four models for the bone sawing process. The results revealed a polynomial dependency between the material removal rate and the applied force. Differences between the three segments of the osteotomy line and between the cortical and cancellous bone were highlighted.
We present an electromechanically coupled Finite Element model for cardiac tissue. It bases on the mechanical model for cardiac tissue of Hunter et al. that we couple to the McAllister-Noble-Tsien electrophysiological model of purkinje fibre cells. The corresponding system of ordinary differential equations is implemented on the level of the constitutive equations in a geometrically and physically nonlinear version of the so-called edge-based smoothed FEM for plates. Mechanical material parameters are determined from our own pressure-deflection experimental setup. The main purpose of the model is to further examine the experimental results not only on mechanical but also on electrophysiological level down to ion channel gates. Moreover, we present first drug treatment simulations and validate the model with respect to the experiments.
The possibility of using the atomic-force microscopy as a method for detection of the analytical signal from plasticized polymeric sensor membranes was analyzed. The surfaces of cadmium-selective membranes based on two polymeric matrices were examined. The digital images were processed with multivariate image analysis techniques. A correlation was found between the surface profile of an ion-selective membrane and the concentration of the ion in solution.
A new trend in automation is to deploy so-called cyber-physical systems (CPS) which combine computation with physical processes. The novel RoboCup Logistics League Sponsored by Festo (LLSF) aims at such CPS logistic scenarios in an automation setting. A team of robots has to produce products from a number of semi-finished products which they have to machine during the game. Different production plans are possible and the robots need to recycle scrap byproducts. This way, the LLSF is a very interesting league offering a number of challenging research questions for planning, coordination, or communication in an application-driven scenario. In this paper, we outline the objectives of the LLSF and present steps for developing the league further towards a benchmark for logistics scenarios for CPS. As a major milestone we present the new automated referee system which helps in governing the game play as well as keeping track of the scored points in a very complex factory scenario.
IT Products are viewed and managed differently depending on the perspectives and the stage within the life cycle. A model is presented that integrates different perspectives and stages serving as an aid for the analysis of business models and focused positioning of IT-products. Four generic business models are analysed with regard to the product management function in general and the positioning field for IT-products specifically: off-the-shelf (license), license plus service, project, and system service (incl. cloud computing).
Heat production in the windings of the stators of electric machines under stationary condition
(2014)
In electric machines due to high currents and resistive losses (joule heating) heat is produced. To avoid damages by overheating the design of effective cooling systems is required. Therefore the knowledge of heat sources and heat transfer processes is necessary. The purpose of this paper is to illustrate a good and effective calculation method for the temperature analysis based on homogenization techniques. These methods have been applied for the stator windings in a slot of an electric machine consisting of copper wires and resin. The key quantity here is an effective thermal conductivity, which characterizes the heterogeneous wire resin-arrangement inside the stator slot. To illustrate the applicability of the method, the analysis of a simplified, homogenized model is compared with the detailed analysis of temperature behavior inside a slot of an electric machine according to the heat generation. We considered here only the stationary situation. The achieved numerical results are accurate and show that the applied homogenization technique works in practice. Finally the results of simulations for the two cases, the original model of the slot and the homogenized model chosen for the slot (unit cell), are compared to experimental results.
A technology reference study for a solar polar mission is presented. The study uses novel analytical methods to quantify the mission design space including the required sail performance to achieve a given solar polar observation angle within a given timeframe and thus to derive mass allocations for the remaining spacecraft sub-systems, that is excluding the solar sail sub-system. A parametric, bottom-up, system mass budget analysis is then used to establish the required sail technology to deliver a range of science payloads, and to establish where such payloads can be delivered to within a given timeframe. It is found that a solar polar mission requires a solar sail of side-length 100–125 m to deliver a ‘sufficient value’ minimum science payload, and that a 2.5 μm sail film substrate is typically required, however the design is much less sensitive to the boom specific mass.
A technology reference study for a displaced Lagrange point space weather mission is presented. The mission builds on previous concepts, but adopts a strong micro-spacecraft philosophy to deliver a low mass platform and payload which can be accommodated on the DLR/ESA Gossamer-3 technology demonstration mission. A direct escape from Geostationary Transfer Orbit is assumed with the sail deployed after the escape burn. The use of a miniaturized, low mass platform and payload then allows the Gossamer-3 solar sail to potentially double the warning time of space weather events. The mission profile and mass budgets will be presented to achieve these ambitious goals.
A technology reference study for a multiple near-Earth object (NEO) rendezvous mission with solar sailcraft is currently carried out by the authors of this paper. The investigated mission builds on previous concepts, but adopts a strong micro-spacecraft philosophy based on the DLR/ESA Gossamer technology. The main scientific objective of the mission is to explore the diversity of NEOs. After direct interplanetary insertion, the solar sailcraft should—within less than 10 years—rendezvous three NEOs that are not only scientifically interesting, but also from the point of human spaceight and planetary defense. In this paper, the objectives of the study are outlined and a preliminary potential mission profile is presented.
The development of Gossamer sail structures for solar sails contributes to a large field of future space applications like thin film solar generators, membrane antennas and drag sails. The focus of this paper is the development of a drag sail based on solar sail technology that could contribute to a reduction of space debris in low Earth orbits. The drag sail design and its connections to solar sail development, a first test on a sounding rocket, as well as the ongoing integration of the drag sail into a triple CubeSat is presented.
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.
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.
Biopharmaceuticals such as antibodies are produced in cultivated mammalian cells, which must be monitored to comply with good manufacturing practice. We, therefore, developed a fully automated system comprising a specific exhaust gas analyzer, inline analytics and a corresponding algorithm to precisely determine the oxygen uptake rate, carbon dioxide evolution rate, carbon dioxide transfer rate, transfer quotient and respiratory quotient without interrupting the ongoing cultivation, in order to assess its reproducibility. The system was verified using chemical simulation experiments and was able to measure the respiratory activity of hybridoma cells and DG44 cells (derived from Chinese hamster ovary cells) with satisfactory results at a minimum viable cell density of ~2.0 × 10⁵ cells ml⁻¹. The system was suitable for both batch and fed-batch cultivations in bubble-aerated and membrane-aerated reactors, with and without the control of pH and dissolved oxygen.
Shakedown analysis of Reissner-Mindlin plates using the edge-based smoothed finite element method
(2014)
This paper concerns the development of a primal-dual algorithm for limit and shakedown analysis of Reissner-Mindlin plates made of von Mises material. At each optimization iteration, the lower bound of the shakedown load multiplier is calculated simultaneously with the upper bound using the duality theory. An edge-based smoothed finite element method (ES-FEM) combined with the discrete shear gap (DSG) technique is used to improve the accuracy of the solutions and to avoid the transverse shear locking behaviour. The method not only possesses all inherent features of convergence and accuracy from ES-FEM, but also ensures that the total number of variables in the optimization problem is kept to a minimum compared with the standard finite element formulation. Numerical examples are presented to demonstrate the effectiveness of the present method.
Hybride Produktionssysteme
(2011)
Während die virtuelle Produktentstehungskette große Gestaltungsfreiräume bietet, ist die reale Produktentstehungskette durch wesentlich mehr Randbedingungen gekennzeichnet, die nicht oder nur ansatzweise beeinflussbar sind. Die Realisierung des aus logistischer Sicht optimalen One-Piece-Flow bei gleichzeitiger Steigerung von Flexibilität und Produktivität sowie des Verschiebens der Grenze des technologisch Machbaren müssen in zukünftigen Forschungsansätzen gleichermaßen betrachtet werden. Die Grenzverschiebung auf Basis der Integration von Technologien ist dabei ein viel versprechender Ansatz, der es in vielen Fällen ermöglicht, in allen genannten Zielrichtungen gleichermaßen Potentiale zu erschließen.
Mikrokleben
(2005)
"To assess the habitability of the icy environments in the solar system, for example, on Mars, Europa, and Enceladus, the scientific analysis of material embedded in or underneath their ice layers is very important. We consider self-steering robotic ice melting probes to be the best method to cleanly access these environments, that is, in compliance with planetary protection standards. The required technologies are currently developed and tested."
The investigation of atomic resonance fluorescence has always been of special interest as a means for the determination of atomic parameters. In addition, information on the interaction mechanism between atoms and radiation can be obtained. In the standard fluorescence experiment the frequency distribution of the incident photons is larger than the natural width of the respective transition; as a consequence the correlation time in the photon-atom interaction is determined by the lifetime of the atoms in the excited state. With the development of lasers and especially of tunable dye lasers in recent years it became possible to study the case where the incident radiation has a spectral distribution which is narrower than the natural width. This corresponds to a correlation time of the incoming light wave which is much longer than the excited-state lifetime. In this chapter a survey of experiments on the resonance fluorescence of atoms in monochromatic laser fields will be given.
The semiconductor field-effect platform represents a powerful tool for detecting the adsorption and binding of charged macromolecules with direct electrical readout. In this work, a capacitive electrolyte–insulator–semiconductor (EIS) field-effect sensor consisting of an Al-p-Si-SiO2 structure has been applied for real-time in situ electrical monitoring of the layer-by-layer formation of polyelectrolyte (PE) multilayers (PEM). The PEMs were deposited directly onto the SiO2 surface without any precursor layer or drying procedures. Anionic poly(sodium 4-styrene sulfonate) and cationic weak polyelectrolyte poly(allylamine hydrochloride) have been chosen as a model system. The effect of the ionic strength of the solution, polyelectrolyte concentration, number and polarity of the PE layers on the characteristics of the PEM-modified EIS sensors have been studied by means of capacitance–voltage and constant-capacitance methods. In addition, the thickness, surface morphology, roughness and wettabilityof the PE mono- and multilayers have been characterised by ellipsometry, atomic force microscopy and water contact-angle methods, respectively. To explain potential oscillations on the gate surface and signal behaviour of the capacitive field-effect EIS sensor modified with a PEM, a simplified electrostatic model that takes into account the reduced electrostatic screening of PE charges by mobile ions within the PEM has been proposed and discussed.
In the Collaborative Research Center SFB 401 at RWTH Aachen University, the numerical aeroelastic method SOFIA for direct numerical aeroelastic simulation is being progressively developed. Numerical results obtained by applying SOFIA were compared with measured data of static and dynamic aeroelastic wind tunnel tests for an elastic swept wing in subsonic flow.
In this part of the MEGADESIGN project, aeroelastic effects are introduced into the aerodynamic analysis of aircrafts by coupling DLR’s flow solvers TAU and FLOWer to a Timoshenko-beam solver. The emerging aeroelastic solvers and a method for the automatic identification of Timoshenko-beam models for wing-box structures were integrated into a simulation environment enabling the combined optimisation of aerodynamic wing shape and structure.
Die Fahrzeugkarosserie bildet als größte funktionale und organisatorische Systemeinheit ein zentrales Kompetenzfeld der OEMs. Für den Fahrzeughersteller stellt der Karosserierohbau eine hohe Kernkompetenz sowohl in der Produktentwicklung als auch in der Produktion dar. Neue, innovative Karosseriebauweisen, bspw. aufgrund eines neuen Fahrzeugkonzeptes oder neuer Anforderungen, bedeuten für den OEM auch gleichzeitig die intensive Auseinandersetzung mit Kompetenzfokussierung bzw. Wertschöpfungsverlagerungen.
Temperature-dependent ranges of coexistence in a model of a two-prey-one-predator microbial food web
(2012)
The objective of our study was to analyze the effects of temperature on the population dynamics of a three-species food web consisting of two prey bacteria (Pedobacter sp. and Acinetobacter johnsonii) and a protozoan predator (Tetrahymena pyriformis) as model organisms. We assessed the effects of temperature on the growth rates of all three species with the objective of developing a model with four differential equations based on the experimental data. The following hypotheses were tested at a theoretical level: Firstly, temperature changes can affect the dynamic behavior of a system by temperature-dependent parameters and interactions and secondly, food web response to temperature cannot be derived from the single species temperature response. The main outcome of the study is that temperature changes affect the parameter range where coexistence is possible within all three species. This has significant consequences on our ideas regarding the evaluation of effects of global warming.
Der Verein Deutscher Ingenieure e.V. (VDI) ist ein gemeinnütziger, wirtschaftlich und politisch unabhängiger, technisch-wissenschaftlicher Verein von Ingenieuren und Naturwissenschaftlern. Mit über 137 000 persönlich zugeordneten Mitgliedern ist er eine der größten Ingenieur-Vereinigungen Europas und gilt in Deutschland als führender Sprecher der Technik und der Ingenieure. 1856 gegründet, hat er viele für die Technik wesentliche Entwicklungen in Gang gesetzt, so im Bereich der technischen Überwachung, der technischen Regelsetzung und Normung, der Arbeitsstudien, im gewerblichen Rechtsschutz und im Patentwesen. Seit seiner Gründung sieht es der VDI als seine Aufgabe, "das Zusammenwirken aller geistiger Kräfte der Technik im Bewusstsein ethischer Verantwortung zu fördern" und die Lebensmöglichkeiten aller Menschen durch Entwicklung und sinnvoller Anwendung technischer Mittel zu verbessern.
Often, detailed simulations of heat conduction in complicated, porous media have large runtimes. Then homogenization is a powerful tool to speed up the calculations by preserving accurate solutions at the same time. Unfortunately real structures are generally non-periodic, which requires unpractical, complicated homogenization techniques. We demonstrate in this paper, that the application of simple, periodic techniques to realistic media, that are just close to periodic, gives accurate, approximative solutions. In order to obtain effective parameters for the homogenized heat equation, we have to solve a so called “cell problem”. In contrast to periodic structures it is not trivial to determine a suitable unit cell, which represents a non-periodic media. To overcome this problem, we give a rule of thumb on how to choose a good cell. Finally we demonstrate the efficiency of our method for virtually generated foams as well as real foams and compare these results to periodic structures.
Partikelmesstechnik
(2012)
Der Schutz von Produkten vor der Kontamination durch Partikel gilt als eine zentrale Aufgabe der Reinraumtechnik. Da es dabei um Kontaminationseffekte weit unterhalb der visuellen Wahrnehmbarkeit geht, braucht es leistungsfähige Verfahren, um die Messgröße „Partikelkontamination“ über den gesamten Bereich, den Anwender fordern, präzise zu bestimmen. Neben der Partikelhäufigkeit ist dabei die Größe der Partikel, die sowohl das Transportverhalten wie auch die mögliche Wirkung auf das Produkt beeinflusst, von entscheidender Bedeutung. Ferner kann es für die Ermittlung von Kontaminationsquellen von Interesse sein, die Form und die chemische Natur der Partikel zu bestimmen (z. B. textile Fasern, Metallabrieb, flüssige Tröpfchen). Die Partikelhäufigkeit wird üblicherweise als Konzentration, d. h. bezogen auf das analysierte Gasvolumen angegeben. Bei den in reinen Technologien üblichen niedrigen Konzentrationen dient als Häufigkeitsmaß die Partikelanzahlkonzentration, also die Partikelanzahl pro Volumeneinheit des Trägermediums.
Ein 34-jähriger männlicher Patient stellte sich zur Abklärung einer seit dem 9. Lebensjahr bestehenden und im letzten Jahr rasch progredienten Visusminderung beider Augen bei uns vor. Er beschrieb eine subjektiv zunehmende, im Spiegel für ihn selbst sichtbare, weißliche Trübung in der Pupille beidseits und eine starke Blendempfindlichkeit. Nebenbefundlich gab er rezidivierende Konjunktivitiden und morgens verklebte Lider an. Eine Allergie auf Gräserpollen und eine Unverträglichkeit auf Alkohol sowie mehrere Lebensmittel seien ebenfalls bekannt.
Zusätzlich leidet der Patient an stark ausgeprägtem atopischem Ekzem. Dieses wurde nie systemisch, sondern nur bei Bedarf mit kortisonhaltiger Salbe therapiert.
Bilaterale stromale Hornhauttrübungen sind für den Augenarzt eine differenzialdiagnostische Herausforderung. Im folgenden Beitrag werden 2 Patieninnen (30 und 36 Jahre) mit unterschiedlich stark ausgeprägter stromaler diffuser Hornhauttrübung vorgestellt. Patientin 1 war kleinwüchsig (114 cm) und Patientin 2 normal groß (172 cm). Beide Patientinnen wiesen veränderte Gelenkstrukturen an Hand und Fußgelenken sowie diffuse stromale Hornhauttrübungen auf. Des Weiteren lagen eine Mitral- und Aorteninsuffizienz (Patientin 1) bzw. eine Aorteninsuffizienz (Patientin 2) vor. Die stromalen diffusen Hornhauttrübungen ließen im Zusammenhang mit den Gelenkveränderungen ein Scheie-Syndrom vermuten. Therapeutisch ist bei Patienten mit Visusminderung eine (lamelläre) Keratoplastik sinnvoll.
Arbeitswissenschaft
(2001)
Unter Arbeit wird das Tätigsein des Menschen verstanden, bei dem dieser mit anderen Menschen und (technischen) Hilfsmitteln in Interaktion tritt, um unter wirtschaftlichen Zielsetzungen Güter und Dienstleistungen zu erstellen (Luczak, 1998a). Arbeit dient direkt oder indirekt der Erhaltung der eigenen Existenz und der Existenz der Gesellschaft. Arbeit ist deshalb eine besondere Form des Tätigseins neben anderen wie Spiel, Sport, Lemen usw.
Reasoning with Qualitative Positional Information for Domestic Domains in the Situation Calculus
(2011)
Density Operator
(2009)
This work describes a procedure to yield attenuation maps from MR images which are used for the absorption correction (AC) of brain PET data. Such an approach could be mandatory for future combined PET and MRI scanners, which probably do not include a transmission facility. T1-weighted MR images were segmented into brain tissue, bone, soft tissue, and sinus; attenuation coefficients corresponding to elemental composition and density as well as to 511 keV photon energy were respectively assigned. Attenuation maps containing up to four compartments were created and forward projected into sinograms with attenuation factors which then were used for AC during reconstruction of FDG-PET data. The commonly used AC based on a radioactive (68Ge) transmission scan served as reference. The reconstructed radioactivity values obtained with the MRI-based AC were about 20% lower than those obtained with PET-based AC if the skull was not taken into account. Considering the skull the difference was still about 10%. Our investigations demonstrate the feasibility of a MRI-based AC, but revealed also the necessity of a satisfying delineation of bone thickness which tends to be underestimated in our first approach of T1-weighted MR image segmentation.
In the preceeding chapters on “Son of Concorde, a Technology Challenge” and “Aerodynamic Multipoint Design Challenge” it was explained, that a well balanced contribution of new technologies in all major disciplines is required for realisation of a new Supersonic Commercial Transport (SCT). One of these technologies - usually one of the most important for aircraft-is aerodynamics. Here, the required “pure” aerodynamic technologies are specified in more detail, according to our present knowledge. Increasing insight into the problems may change the balance of importance of the individual technologies and may require some more contributions. We must never confine our knowledge to the knowledge base of an expert at a given time, but must stay open for new insights.
Since certification of Concorde new certification standards were introduced including many new regulations to improve flight safety. Most of these standards are to prevent severe accidents in the future which happened in the past (here: after Concorde’s certification). A new SCT has to fulfill these standards, although Concorde had none of these accidents. But accidents - although they sometimes occurred only for a specific aircraft type - have to be avoided for any (new) aircraft. Because of existing aircraft without typical accident types having demonstrated their reliability, they are allowed to go on based on their old certification; although sometimes new rules prevent accident types which are not connected to specific aircraft types - like e.g. evacuation rules. Anyway, Concorde is allowed to fly based on its old certification, and hopefully in the future will fly as safely as in the past. But a new SCT has to fulfill updated rules like any other aircraft, and it has to be “just another aircraft” [75].
Supersonic laminar flow
(1997)
Supersonic transports are very drag sensitive. Technology to reduce drag by application of laminar flow, therefore, will be important; it is a prerequisite to achieve very long range capability. In earlier studies it was assumed that SCTs would only become possible by application of laminar flow [376]. But today, we request an SCT to be viable without application of laminar flow in order to maintain its competitiveness when laminar flow becomes available for subsonic and supersonic transports. By reducing fuel burned, laminar flow drag reduction reduces size and weight of the aircraft, or increases range capability -whereas otherwise size and weight would grow towards infinity. Transition mechanisms from laminar to turbulent state of the boundary layer flow (ALT, CFI, TSI) function as for transonic transports, but at more severe conditions: higher sweep angles, cooled surfaces; higher mode instabilities (HMI) must at least be taken into account, although they may not become important below Mach 3. Hitherto there is a worldwide lack of ground test facilities to investigate TSI at the expected cruise Mach numbers between 1.6 and 2.4; in Stuttgart, Germany one such facility -a Ludwieg tube- is still in the validation phase. A quiet Ludwieg tunnel could be a favourable choice for Europe. But it will require a new approach in designing aircraft which includes improved theoretical predictions, usage of classical wind tunnels for turbulent flow and flight tests for validation.
Concorde (Figure 9) is the only supersonic airliner which has been introduced into regular passenger service. It is still in service at British Airways and Air France without any flight accidents, and probably will stay in service for at least for ten more years.
In the chapter “Son of Concorde, a Technology Challenge” one of the new challenges for a Supersonic Commercial Transport (SCT) is multi-point design for the four main design points:
- supersonic cruise
- transonic cruise
- take-off and landing
- transonic acceleration.