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Verformungsbasierter seismischer Nachweis von Mauerwerksbauten mit der Kapazitätsspektrum-Methode
(2005)
Aufgrund der gestiegenen Anforderungen durch höhere Ein-wirkungen aus Wind und Erdbeben ist eine Verbesserung und Optimierung der Berechnungs- und Bemessungsansätze für Mauerwerksbauten erforderlich. Eine bessere Ausnutzung der Tragwerksreserven ist durch die Berücksichtigung der Rah-mentragwirkung mit einer Aktivierung der Deckenscheiben in den Rechenmodellen möglich, die in der Praxis aufgrund der Komplexität der Wand-Decken-Interaktion bislang nicht aus-genutzt wird. Im vorliegenden Aufsatz wird ein vereinfachter Ansatz auf Grundlage der mitwirkenden Plattenbreite von Schubwänden aus Mauerwerk vorgestellt, der die wesentli-chen Einfl ussfaktoren in parametrisierten Tabellen erfasst. Damit steht den Tragwerksplanern ein einfach anwendbares Werkzeug zur Verfügung, um die Rahmentragwirkung in der Mauerwerksbemessung anzusetzen.
This paper proposes a quick and simplified method to describe masonry vaults in global seismic analyses of buildings. An equivalent macro-element constituted by a set of six trusses, two for each transverse, longitudinal and diagonal direction, is introduced. The equivalent trusses, whose stiffness is calculated by fully modeled vaults of different geometry, mechanical properties and boundary conditions, simulate the vault in both global analysis and local analysis, such as kinematic or rocking approaches. A parametric study was carried out to investigate the influence of geometrical characteristics and mechanical features on the equivalent stiffness values. The method was numerically validated by performing modal and transient analysis on a three naves-church in the elastic range. Vibration modes and displacement time-histories were compared showing satisfying agreement between the complete and the simplified models. This procedure is particularly useful in engineering practice because it allows to assess, in a simplified way, the effectiveness of strengthening interventions for reducing horizontal relative displacements between vault supports.
The performance and biomass yield of the perennial energy plant Sida hermaphrodita (hereafter referred to as Sida) as a feedstock for biogas and solid fuel was evaluated throughout one entire growing period at agricultural field conditions. A Sida plant development code was established to allow comparison of the plant growth stages and biomass composition. Four scenarios were evaluated to determine the use of Sida biomass with regard to plant development and harvest time: (i) one harvest for solid fuel only; (ii) one harvest for biogas production only; (iii) one harvest for biogas production, followed by a harvest of the regrown biomass for solid fuel; and (iv) two consecutive harvests for biogas production. To determine Sida's value as a feedstock for combustion, we assessed the caloric value, the ash quality, and melting point with regard to DIN EN ISO norms. The results showed highest total dry biomass yields of max. 25 t ha⁻¹, whereas the highest dry matter of 70% to 80% was obtained at the end of the growing period. Scenario (i) clearly indicated the highest energy recovery, accounting for 439 288 MJ ha⁻¹; the energy recovery of the four scenarios from highest to lowest followed this order: (i) ≫ (iii) ≫ (iv) > (ii). Analysis of the Sida ashes showed a high melting point of >1500 °C, associated with a net calorific value of 16.5–17.2 MJ kg⁻¹. All prerequisites for DIN EN ISO norms were achieved, indicating Sida's advantage as a solid energy carrier without any post-treatment after harvesting. Cell wall analysis of the stems showed a constant lignin content after sampling week 16 (July), whereas cellulose had already reached a plateau in sampling week 4 (April). The results highlight Sida as a promising woody, perennial plant, providing biomass for flexible and multipurpose energy applications.
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.
Das Ziel der vorliegenden Arbeit ist die Specklereduktion bei der Infrarotlaser-gestützten abbildenden Ferndetektion von TNT-Oberflächenkontaminationen. Für die Detektion wird die Probenoberfläche mit einem abstimmbaren Quantenkaskadenlaser bei verschiedenen Wellenzahlen im Spektralbereich von 1340cm-1 bis 1380cm-1 bestrahlt, während eine Infrarot-Kamera Bilder der bestrahlten Fläche aufzeichnet. Diese Bilder werden dann so verarbeitet, dass im Ausgabebild die chemisch spezifische TNT-Absorption durch eine Änderung der Helligkeit örtlich aufgelöst erkennbar werden. Da kohärente Strahlung, welche beispielsweise an optisch rauen Oberflächen reflektiert wird, aufgrund der stochastischen Verteilung der Oberflächenrautiefe mit der einfallenden Strahlung lateral unterschiedlich interferiert, entsteht ein „Rauschen“ in der aufgezeichneten Strahlungsleistungsverteilung, das sog. Speckle-Phänomen. Die Empfindlichkeit der oben skizzierten Lasergestützten Messtechnik wird im Wesentlichen durch diesen Effekt limitiert. Um die durch Laserspeckles verursachten Rauschanteile zu reduzieren, gibt es verschiedene Möglichkeiten. Durch Reduktion von zeitlicher und räumlicher Kohärenz der Strahlung wird deren Interferenzfähigkeit reduziert und durch Variieren des Specklemusters während einer Bildaufzeichnung führen Mittelungen unkorrelierter Rauschanteile zu einer Specklekontrastreduktion. Letztere Möglichkeit resultiert daraus, dass Laserspeckles statistisch durch die Familie der Gammaverteilungen beschrieben werden können. Demnach verbessert sich das Signal-zu-Rausch-Verhältnis mit der Anzahl gemittelter, unkorrelierter Rauschmuster proportional zur Wurzel dieser Anzahl. Ein im MIR-Spektralbereich umsetzbarer Ansatz, der all diese Möglichkeiten berücksichtigt, wurde bereits 1971 von Lowenthal und Joyeaux vorgeschlagen und im Rahmen der vorliegenden Arbeit für den infraroten Spektralbereich adaptiert. Dazu wird die Strahlung mit zwei CVD-Diamant-Wafern moduliert; ein Wafer ist dabei stationär und der andere rotiert mit ca. 70Hz. In der vorliegenden Arbeit konnte mit diesem Ansatz eine Verbesserung des Signal-zu-Rausch-Verhältnisses in der betrachteten Strahlungsleistungs¬verteilung von ursprünglich 3 auf etwa 45 erzielt werden. So konnten erstmals TNT-Kontaminationen von bis zu 10µg/cm² in einem Abstand von 5m abbildend nachgewiesen werden. Dies entspricht der Kontamination durch einen mit TNT leicht verunreinigten Fingerabdruck.
The complex questions of today for a world of tomorrow are characterized by their global impact. Solutions must therefore not only be sustainable in the sense of the three pillars of sustainability (economic, environmental, and social) but must also function globally. This goes hand in hand with the need for intercultural acceptance of developed services and products. To achieve this, engineers, as the problem solvers of the future, must be able to work in intercultural teams on appropriate solutions, and be sensitive to intercultural perspectives. To equip the engineers of the future with the so-called future skills, teaching concepts are needed in which students can acquire these methods and competencies in application-oriented formats. The presented course "Applying Design Thinking - Sustainability, Innovation and Interculturality" was developed to teach future skills from the competency areas Digital Key Competencies, Classical Competencies and Transformative Competencies. The CDIO Standard 3.0, in particular the standards 5, 6, 7 and 8, was used as a guideline. The course aims to prepare engineering students from different disciplines and cultures for their future work in an international environment by combining a digital teaching format with an interdisciplinary, transdisciplinary and intercultural setting for solving sustainability challenges. The innovative moment lies in the digital application of design thinking and the inclusion of intercultural as well as trans- and interdisciplinary perspectives in innovation development processes. In this paper, the concept of the course will be presented in detail and the particularities of a digital implementation of design thinking will be addressed. Subsequently, the potentials and challenges will be reflected and practical advice for integrating design thinking in engineering education will be given.
Stored and cooled, highly-charged ions offer unprecedented capabilities for precision studies in the realm of atomic, nuclear structure and astrophysics[1]. After the successful investigation of the 96Ru(p,7)97Rh reaction cross section in 2009[2], the first measurement of the 124Xe(p,7)125Cs reaction cross section has been performed with decelerated, fully-ionized 124Xe ions in 2016 at the Experimental Storage Ring (ESR) of GSI[3]. Using a Double Sided Silicon Strip Detector, introduced directly into the ultra-high vacuum environment of a storage ring, the 125Cs proton-capture products have been successfully detected. The cross section has been measured at 5 different energies between 5.5AMeV and 8AMeV, on the high energy tail of the Gamow-window for hot, explosive scenarios such as supernovae and X-ray binaries. The elastic scattering on the H2 gas jet target is the major source of background to count the (p,7) events. Monte Carlo simulations show that an additional slit system in the ESR in combination with the energy information of the Si detector will enable background free measurements of the proton-capture products. The corresponding hardware is being prepared and will increase the sensitivity of the method tremendously.
TOP-Energy : softwaregestützte Analyse und Optimierung industrieller Energieversorgungssysteme
(2004)
Using optimization to design a renewable energy system has become a computationally demanding task as the high temporal fluctuations of demand and supply arise within the considered time series. The aggregation of typical operation periods has become a popular method to reduce effort. These operation periods are modelled independently and cannot interact in most cases. Consequently, seasonal storage is not reproducible. This inability can lead to a significant error, especially for energy systems with a high share of fluctuating renewable energy. The previous paper, “Time series aggregation for energy system design: Modeling seasonal storage”, has developed a seasonal storage model to address this issue. Simultaneously, the paper “Optimal design of multi-energy systems with seasonal storage” has developed a different approach. This paper aims to review these models and extend the first model. The extension is a mathematical reformulation to decrease the number of variables and constraints. Furthermore, it aims to reduce the calculation time while achieving the same results.
For typical cases of non-isolated lightning protection systems (LPS) the impulse currents are investigated which may flow through a human body directly touching a structural part of the LPS. Based on a basic LPS model with conventional down-conductors especially the cases of external and internal steel columns and metal façades are considered and compared. Numerical simulations of the line quantities voltages and currents in the time domain are performed with an equivalent circuit of the entire LPS.
As a result it can be stated that by increasing the number of conventional down-conductors and external steel columns the threat for a human being can indeed be reduced, but not down to an acceptable limit. In case of internal steel columns used as natural down-conductors the threat can be reduced sufficiently, depending on the low-resistive connection of the steel columns to the lightning equipotential bonding or the earth termination system, resp. If a metal façade is used the threat for human beings touching is usually very low, if the façade is sufficiently interconnected and multiply connected to the lightning equipotential bonding or the earth termination system, resp.
Theoretische und experimentelle Untersuchung der Erwärmung von Metallblechen bei Blitzeinschlag
(1990)
The longitudinal voltage of cable tubes with a screening mesh caused by partial lightning currents
(1989)
The proposed Den Haag Zuidwest district heating system of the city of The Hague consists of a deep doublet in a Jurassic sandstone layer that is designed for a production temperature of 75 °C and a reinjection temperature of 40 °C at a flow rate of 150 m3 h−1. The prediction of reservoir temperature and production behavior is crucial for success of the proposed geothermal doublet. This work presents the results of a study of the important geothermal and geohydrological issues for the doublet design. In the first phase of the study, the influences of the three-dimensional (3D) structures of anticlines and synclines on the temperature field were examined. A comprehensive petrophysical investigation was performed to build a large scale 3D-model of the reservoir. Several bottomhole temperatures (BHTs), as well as petrophysical logs were used to calibrate the model using thermal conductivity measurements on 50 samples from boreholes in different lithological units in the study area. Profiles and cross sections extracted from the calculated temperature field were used to study the temperature in the surrounding areas of the planned doublet. In the second phase of the project, a detailed 3D numerical reservoir model was set up, with the aim of predicting the evolution of the producer and injector temperatures, and the extent of the cooled area around the injector. The temperature model from the first phase provided the boundary conditions for the reservoir model. Hydraulic parameters for the target horizons, such as porosity and permeability, were taken from data available from the nearby exploration wells. The simulation results are encouraging as no significant thermal breakthrough is predicted. For the originally planned location of the producer, the extracted water temperature is predicted to be around 79 °C, with an almost negligible cooling in the first 50 years of production. When the producer is located shallower parts of the reservoir, the yield water temperatures is lower, starting at ≈76 °C and decreasing to ≈74 °C after 50 years of operation. This comparatively larger decrease in temperature with time is caused by the structural feature of the reservoir, namely a higher dip causes the cooler water to easily move downward. In view of the poor reservoir data, the reservoir simulation model is constructed to allow iterative updates using data assimilation during planned drilling, testing, and production phases. Measurements during an 8 h pumping test carried out in late 2010 suggest that a flow rate of 150 m3 h−1 is achievable. Fluid temperatures of 76.5 °C were measured, which is very close to the predicted value.
The Effect of Openings on Out-of-Plane Capacity of Masonry Infilled Reinforced Concrete Frames
(2018)
Cryopumps without liquid nitrogen shielding are used to provide a vacuum of 10−6 torr in the spectrometer. The vacuum system is subdivided in three sections that can be separated by valves.
The first section (scattering chamber) has a volume of 60 l, two rotation transmissions with 35 cm dia and a sliding seal that allows a rotation of 160° without deteriorating the vacuum. The second section includes the vacuum chambers inside the magnets with 6 × 80 cm cross-section and a length of 1200 cm. The third section (detector box) has a volume of 4300 l and contains a moveable detector system. The gas inside the detector with a pressure of 760 torr is separated from the vacuum by a 15 μm mylar foil with an area of 300 cm2. The detector box can be valved off by a valve with the dimension of 10 × 100 cm.
The layout of system is given. The instrumentation and the interlock system are described. First experiences with this system are presented.
With proven impact of statistical fracture analysis on fracture classifications, it is desirable to minimize the manual work and to maximize repeatability of this approach. We address this with an algorithm that reduces the manual effort to segmentation, fragment identification and reduction. The fracture edge detection and heat map generation are performed automatically. With the same input, the algorithm always delivers the same output. The tool transforms one intact template consecutively onto each fractured specimen by linear least square optimization, detects the fragment edges in the template and then superimposes them to generate a fracture probability heat map.
We hypothesized that the algorithm runs faster than the manual evaluation and with low (< 5 mm) deviation. We tested the hypothesis in 10 fractured proximal humeri and found that it performs with good accuracy (2.5 mm ± 2.4 mm averaged Euclidean distance) and speed (23 times faster). When applied to a distal humerus, a tibia plateau, and a scaphoid fracture, the run times were low (1–2 min), and the detected edges correct by visual judgement. In the geometrically complex acetabulum, at a run time of 78 min some outliers were considered acceptable. An automatically generated fracture probability heat map based on 50 proximal humerus fractures matches the areas of high risk of fracture reported in medical literature.
Such automation of the fracture analysis method is advantageous and could be extended to reduce the manual effort even further.
The adsorption of fluor-carbon complexes on GaAs(110) studied by electron energy loss spectroscopy
(1986)
Textile reinforced concrete. Part I: Process model for collaborative research and development
(2003)
One of the most important parameters in a burning chamber - in power stations, in waste to energy plants - is the temperature. This temperature is in the range of 700-1500 °C - one of the most advanced measuring methods being the acoustic pyrometry with the possibility of producing temperature mapping in one level of the burning chamber - comparable to computer tomography. The results of these measurements discussed in the presentation can be used - to fulfil the legal requirements in the FRG or in the EU - to equalise the temperature in one level of the burning chamber to optimise the steam production (better efficiency of the plant) and to minimise the production of temperature controlled flue gas components (NO, CO a. o.) - to control the SNCR-process if used.
Technisches Zeichnen : Lösungsvorschläge für das Selbststudium. (Berichte aus dem Maschinenbau)
(2012)
Technical assessment of Brayton cycle heat pumps for the integration in hybrid PV-CSP power plants
(2022)
The hybridization of Concentrated Solar Power (CSP) and Photovoltaics (PV) systems is a promising approach to reduce costs of solar power plants, while increasing dispatchability and flexibility of power generation. High temperature heat pumps (HT HP) can be utilized to boost the salt temperature in the thermal energy storage (TES) of a Parabolic Trough Collector (PTC) system from 385 °C up to 565 °C. A PV field can supply the power for the HT HP, thus effectively storing the PV power as thermal energy. Besides cost-efficiently storing energy from the PV field, the power block efficiency of the overall system is improved due to the higher steam parameters. This paper presents a technical assessment of Brayton cycle heat pumps to be integrated in hybrid PV-CSP power plants. As a first step, a theoretical analysis was carried out to find the most suitable working fluid. The analysis included the fluids Air, Argon (Ar), Nitrogen (N2) and Carbon dioxide (CO2). N2 has been chosen as the optimal working fluid for the system. After the selection of the ideal working medium, different concepts for the arrangement of a HT HP in a PV-CSP hybrid power plant were developed and simulated in EBSILON®Professional. The concepts were evaluated technically by comparing the number of components required, pressure losses and coefficient of performance (COP).
This paper describes two courses on
simulation methods for graduate students:
“Simulation Methods” and “Simulation and
Optimization in Virtual Engineering” The
courses were planned to teach young engineers
how to work with simulation software as well as
to understand the necessary mathematical background.
As simulation software COMSOL is
used. The main philosophy was to combine
theory and praxis in a way that motivates the
students. In addition “soft skills” should be
improved. This was achieved by project work as
final examination. As underlying didactical principle
the ideas of Bloom’s revised taxonomy
were followed. The paper basically focusses on
educational aspects, e.g. how to structure the
course, plan the exercises, organize the project
work and include practical COMSOL examples.