Refine
Year of publication
Document Type
- Article (226)
- Announcement (104)
- Conference Proceeding (99)
- Part of a Book (43)
- Workingpaper / Report (24)
- Article trade magazine (21)
- Doctoral Thesis (4)
- Book (3)
- Collection (3)
- Course Material (3)
Keywords
- Amtliche Mitteilungen (101)
- Prüfungsrecht (77)
- Prüfungsordnung (66)
- Bachelor (41)
- Master (41)
- MV (31)
- Maschinenbau (30)
- Änderung (29)
- DOAJ (22)
- Satzung (21)
Department/institution
- Fachbereich - Maschinenbau und Verfahrenstechnik (539) (remove)
This article is on a university course called Engineering Conferences. It has been developed by the authors and installed as a mandatory part of the curriculum in three master’s degree programs for engineering students. The participants of the course are postgraduates with different nationalities, mostly German, and different technical backgrounds. They study Mechanical Engineering, Simulation and Experimental Technology, or International Business Engineering. The basic idea of the course concept goes far beyond simply teaching the standards of academic writing and skills for using scientific publications. By using a learnercentered approach, the students get engaged in typical activities around an active attendance of a real conference. Students learn to locate the field of their bachelor thesis or project report in the world of research communities, scientific journals and engineering conferences. They learn about conferences matching their bachelor/project topic. They write a paper complying with common academic standards, submit it to a mock-up conference, and review submissions of their fellow students. Students also produce a poster and have to defend it in a poster session held publicly on the campus. Engineering Conferences is a course on scientific communication and presentation that also aims at the development of other skills and competences needed in the world of modern engineering.
Um bauliche Veränderungen in bestehenden Kraftwerksprozessen auf ihre Wirkungsweise untersuchen und thermodynamisch beziehungsweise wirtschaftlich bewerten zu können, werden thermische Kraftwerksprozesse mit geeigneter Simulationssoftware abgebildet und in verschiedenen Detaillierungsstufen ausgelegt oder nachgerechnet. Im Folgenden wird ein Weg aufgezeigt, wie mit Hilfe einer stationären Simulationssoftware die Gesamtjahresbilanz eines Kraftwerks vorausberechnet werden kann. Mit Hilfe von Prozessdaten aus Vorjahren wird nachgewiesen, dass das Berechnungsmodell das bestehende Kraftwerk mit einer Abweichung von weniger als drei Prozent bezüglich erzeugter elektrischer Leistung und Brennstoffeinsatz und bei bekannter Dampfproduktion abbilden kann. Das so verifizierte Modell kann zur Untersuchung von Zubaumaßnahmen oder Veränderungen im Kraftwerksprozess eingesetzt werden.
Wärme: Zuverlässige Kollektoren liefern hohe Solarerträge: Monitoring von Solarthermieanlagen
(2017)
Die Studie des Competence Center Food & Retail (CCFR) der Cologne Business School (CBS) ermittelt Erfolgsfaktoren, Konsumententypen und Handlungsempfehlungen für den Online-Handel mit Lebensmitteln in Deutschland. Grundlage der vorliegenden Studie ist eine im Sommer 2014 durchgeführte onlinebasierte Verbraucherbefragung zum Thema „Online-Kauf von Lebensmitteln“.
eFood in Deutschland
(2015)
Im Vergleich zu „Pionierbranchen“ wie Mode oder Medien steht der Online-Handel mit Lebensmitteln erst am Anfang. Dabei kann dieser zu einem Wettbewerbsvorteil werden – wenn der Handel es richtig angeht. Auf der anderen Seite steht das Risiko einer strategischen Falle, d.h. es wird unter Umständen aufgrund der Widerstände beim Verbraucher nur ein Nischenmarkt bedient, der eine geringe Profitabilität aufweist. Im Spannungsfeld „Marktpotenzial auf Handelsseite“ vs. „Zurückhaltung beim Verbraucher“ rücken dabei Fragen der Kommunikationspolitik im Online-Lebensmittelhandel in den Fokus. Für eine erfolgreiche Umsetzung stellt eine eindeutige Typologie eine notwendige Basis dar, um die konkreten Bedürfnisse potenzieller Konsumenten anzusprechen. Ein Engagement im eFood-Bereich ist daher als Investition in die zukünftige Entwicklung der Märkte und ihrer Zielgruppen zu betrachten. Although online trading in the food sector is still in early stages, it may become a competitive edge – if retailers go about it the right way. On the other hand, due to consumer resistance, there is the risk of serving only a niche market, which cannot be maintained in terms of profitability. Therefore, a stronger focus on communication policies is needed. Engaging in the eFood sector finally has to be seen as an important investment into future markets and their target groups. Keywords: online lebensmittelhandel, lieferfenster, informationszeitalter, face to the customer
Computational models for the personalized analysis of human femurs contain uncertainties in bone material properties and loads, which affect the simulation results. To quantify the influence we developed a probabilistic framework based on polynomial chaos (PC) that propagates stochastic input variables through any computational model. We considered a stochastic E-ρ relationship and a stochastic hip contact force, representing realistic variability of experimental data. Their influence on the prediction of principal strains (ϵ1 and ϵ3) was quantified for one human proximal femur, including sensitivity and reliability analysis. Large variabilities in the principal strain predictions were found in the cortical shell of the femoral neck, with coefficients of variation of ≈40%. Between 60 and 80% of the variance in ϵ1 and ϵ3 are attributable to the uncertainty in the E-ρ relationship, while ≈10% are caused by the load magnitude and 5-30% by the load direction. Principal strain directions were unaffected by material and loading uncertainties. The antero-superior and medial inferior sides of the neck exhibited the largest probabilities for tensile and compression failure, however all were very small (pf<0.001). In summary, uncertainty quantification with PC has been demonstrated to efficiently and accurately describe the influence of very different stochastic inputs, which increases the credibility and explanatory power of personalized analyses of human proximal femurs.
A 3-stage model of a low pressure steam turbine has been equipped with extensive instrumentation to assess aerodynamic performance and for validation of numerical methods. Emphasis was placed on detailed measurements at the inlet and exit of the last stage guide vane. Two configurations were examined – the first used a guide vane with lean in the last stage and a the second used a guide vane combining both lean and sweep. The experimental results from the two configurations have been compared with data from various design methods, ranging from through-flow to 3D multistage viscous simulations with mixing planes. Despite the challenges in modelling complex rotating blades in a wet steam environment, good agreement between the numerical and experimental results was obtained, and the new stator vane combining lean and sweep achieved the desired increase in reaction at the hub section.
Magnetic Resonance (MR) elastography is a method for measuring tissue elasticity via phase images acquired with an MR scanner. The propagation of periodic mechanical waves through the tissue can be captured by means of a modified phase contrast sequence. These waves are generated with a mechanical oscillator (actuator) and coupled into the tissue through the skin. The actuator must be capable of generating a sinusoidal excitation with excellent phase and amplitude stability, while not disturbing the MR imaging process. In this work, an actuator based on a piezoelectric principle was developed. Based on the imaging evaluation of several material samples, the housing for the piezoelectric ceramic was constructed of aluminum. Smaller parts of the housing were manufactured from brass and titanium to fulfill the mechanical constraints. A lever was used to transfer the oscillation generated by the piezoelectric ceramic to the point of excitation. The lever amplifies the piezoelectric motion, allowing for a more compact design. Three different lever designs were characterized by an acceleration sensor both outside and inside the magnet. It was shown that the rigidity of the lever, as determined by its material and form, was decisive in determining the resonant frequency of the system and therefore the maximum practical frequency of operation. It was also shown that the motion of the oscillator is unaffected by the electromagnetic fields of the MR imager. The final design can be placed directly in the magnet bore within a few centimeters of the tissue volume to be imaged without generating significant artifacts. An amplitude range of 0–1 mm in the frequency range from 0 to over 300 Hz was achieved, sufficient for performing most MR elastography applications. © 2002 Wiley Periodicals, Inc. Concepts in Magnetic Resonance (Magn Reson Engineering) 15: 239–254, 2002
We present an approach to feature extraction that is a generalization of the classical linear discriminant analysis (LDA) on the basis of deep neural networks (DNNs). As for LDA, discriminative features generated from independent Gaussian class conditionals are assumed. This modeling has the advantages that the intrinsic dimensionality of the feature space is bounded by the number of classes and that the optimal discriminant function is linear. Unfortunately, linear transformations are insufficient to extract optimal discriminative features from arbitrarily distributed raw measurements. The generalized discriminant analysis (GerDA) proposed in this paper uses nonlinear transformations that are learnt by DNNs in a semisupervised fashion. We show that the feature extraction based on our approach displays excellent performance on real-world recognition and detection tasks, such as handwritten digit recognition and face detection. In a series of experiments, we evaluate GerDA features with respect to dimensionality reduction, visualization, classification, and detection. Moreover, we show that GerDA DNNs can preprocess truly high-dimensional input data to low-dimensional representations that facilitate accurate predictions even if simple linear predictors or measures of similarity are used.
Heterogeneous catalysts usually consist of porous, inorganic materials. Especially in the mobile application, e.g., in exhaust gas catalysis as a part of the gas line of an engine, there are loads due to vibrations and high gas velocities. It can be assumed that physical stress will lead to a loss of the catalytically active coating. The present contribution describes experimental setups and methods for a systematic and reproducible investigation of the main influences to the mass loss due to vibrational and fluid‐mechanical stress caused by particle‐free gas flows.
Impact of Renewable Energy Expansion to the Balancing Energy Demand of Differential Balancing Groups
(2018)
The research addresses the present situation on the German electricity market caused by variable renewable energy sources. The increasing number of households with photovoltaic and battery storage systems and their impacts require special attention. These systems change the traditional electricity customer from the sole electricity consumer to an electricity producer and consumer in one person. These so-called prosumers differ in their actual electricity demand from the initially estimated electricity demand with standard load profile. This discrepancy results in deviations within a differential balancing group. Thereby, the main finding of this research is a significant higher balancing energy demand with the expansion of photovoltaic and battery storage systems. Hence, the standard load profile is particularly not suitable for differential balancing groups with a high penetration of solar systems and still less suitable for groups with solar and battery storage systems
This paper investigates the implementation of a human body model for the simulation of a jumping motion in Simulink. It contains details to get an insight into modern biomechanics without previous experience. In the simulation, a Hill-Type muscle is used to generate joint momentum with a phenomenologically realistic relationship between muscle length and force. The simulation published with this article is one of many solutions to design a humanoid simulation. The paper guides through the implemented build and explains its range of application.
Eye tracking is a measurement technique for determining the orientation and viewing direction of an individual’s eyes. It allows for an evaluation of the individual’s gaze and other related information.There is a wide variety of application areas for eye tracking, however the usage in engineeringindustry is still limited. This paper presents a case study for the use of eye tracking in a testingstation for electrical circuit breakers. The case study aims to evaluate the measurement and analysispossible with the Tobii wearable eye tracking system. From the case study, possibilities, limitationsand considerations for eye tracking in industrial settings are identified and discussed. The paperconcludes that while eye tracking can be used to effectively capture and visualize insightfulinformation, it faces major challenges related to subjectivity in analysis and labour intensiveness.
Small and large deformation analysis with the p- and B-spline versions of the Finite Cell Method
(2012)
The article argues that European innovators can profit from some of the concepts of philosophical Daoism, namely "wu-wei" (non-interference) and "ziran" ("go with the flow"). Whereas most Western approaches to innovation emphasize the different stages of the creative process as well as tools to enhance creativity, the Daoist world view allows for the mind to just wander and thus spontaneously discover the solution to a problem in a rather detached state of mind. Creative minds need space for personal development and the permission to wander around without being exposed to control and instant judgement on the results. Training individuals in the tools and techniques of problem solving and creativity as the common approach in innovation management is certainly necessary, but in the end it is the intellectual accomplishment of a creative mind that produces innovation. Managers can allow this to happen when they get the balance of control and non-interference right.
The organic Rankine cycle (ORC) is an established thermodynamic process that converts waste heat to electric energy. Due to the wide range of organic working fluids available the fluid selection adds an additional degree of freedom to the early design phase of an ORC process. Despite thermodynamic aspects such as the temperature level of the heat source, other technical, economic and safety aspects have to be considered. For the fluid selection process in this paper, 22 criteria were identified in six main categories while distinguishing between elimination and tolerance criteria. For an ORC design, the suggested method follows a practical engineering approach and can be used as a structured way to limit the number of interesting working fluids before starting a detailed performance analysis of the most promising candidates. For the first time the selection process is applied to a two-stage reference cycle which uses the waste heat of a large reciprocating engine for cogeneration power plants. It consists of a high temperature and a low temperature cycle in which the condensation heat of the high temperature (HT) cycle provides the heat input of the low temperature (LT) cycle. After the fluid selection process the detailed thermodynamic cycle design is carried out with a thermodynamic design tool that also includes a database for organic working fluids. The investigated ORC cycle shows a net thermal efficiency of about 17,4% in the high temperature cycle with Toluene as the working fluid and 6,2% in low temperature cycle with iso-Butane as the working fluid. The electric efficiency of the cogeneration plant increases from 40,4% to 46,97% with the both stages of the two-stage ORC in operation.
The organic Rankine cycle (ORC) is an established thermodynamic process that converts waste heat to electric energy. Due to the wide range of organic working fluids available the fluid selection adds an additional degree-of-freedom to the early design phase of an ORC process. Despite thermodynamic aspects such as the temperature level of the heat source, other technical, economic, and safety aspects have to be considered. For the fluid selection process in this paper, 22 criteria were identified in six main categories while distinguishing between elimination (EC) and tolerance criteria (TC). For an ORC design, the suggested method follows a practical engineering approach and can be used as a structured way to limit the number of interesting working fluids before starting a detailed performance analysis of the most promising candidates. For the first time, the selection process is applied to a two-stage reference cycle, which uses the waste heat of a large reciprocating engine for cogeneration power plants. It consists of a high temperature (HT) and a low temperature (LT) cycle in which the condensation heat of the HT cycle provides the heat input of the LT cycle. After the fluid selection process, the detailed thermodynamic cycle design is carried out with a thermodynamic design tool that also includes a database for organic working fluids. The investigated ORC cycle shows a net thermal efficiency of about 17.4% in the HT cycle with toluene as the working fluid and 6.2% in LT cycle with isobutane as the working fluid. The electric efficiency of the cogeneration plant increases from 40.4% to 46.97% with the both stages of the two-stage ORC in operation.
Innovation Spaces: Einfluss der physischen Arbeitsumgebung auf kreatives Denken in Büroumgebungen
(2020)
Das vorliegende Working Paper untersucht den Einfluss der physischen Arbeitsumgebung auf die Kreativität in Unternehmen. Dabei werden sowohl Aspekte der individuellen Kreativität als auch der Corporate Creativity (organisationalen Kreativität) betrachtet. Das Ergebnis ist eine Raumtypologie, die Funktionen eines Raumes in die beiden Achsen „Handeln vs. Geschehen-Lassen“ und „Rückzug vs. Begegnung“ einteilt und dadurch vier unterschiedliche Raumtypen im Hinblick auf die Kreativität unterscheidet. Diese vier Raumtypen sind die Grundlage für das Verständnis von Innovation Spaces – räumlichen Flächen im Unternehmen, die die Kreativ- und Ideenarbeit unterstützen. Das Wirken und die Ausgestaltung dieser unterschiedlichen Funktionen wird anhand von zwei Umsetzungsbeispiele von realisierten Innovation Spaces dargestellt und anhand der Ergebnisse einer Studie zu Akzeptanz und Erfolg von Innovation Spaces untersucht. Daraus werden Handlungsempfehlungen an Unternehmen herausgearbeitet, die Innovation Spaces als Teil einer Innovationskultur im Kontext von New Work begreifen.
Airborne volcanic ash particles are a known hazard to aviation. Currently, there are no means available to detect ash in flight as the particles are too fine (radii < 30 μm) for on-board radar detection and, even in good visibility, ash clouds are difficult or impossible to detect by eye. The economic cost and societal impact of the April/May 2010 Icelandic eruption of Eyjafjallajökull generated renewed interest in finding ways to identify airborne volcanic ash in order to keep airspace open and avoid aircraft groundings. We have designed and built a bi-spectral, fast-sampling, uncooled infrared camera device (AVOID) to examine its ability to detect volcanic ash from commercial jet aircraft at distances of more than 50 km ahead. Here we report results of an experiment conducted over the Atlantic Ocean, off the coast of France, confirming the ability of the device to detect and quantify volcanic ash in an artificial ash cloud created by dispersal of volcanic ash from a second aircraft. A third aircraft was used to measure the ash in situ using optical particle counters. The cloud was composed of very fine ash (mean radii ~10 μm) collected from Iceland immediately after the Eyjafjallajökull eruption and had a vertical thickness of ~200 m, a width of ~2 km and length of between 2 and 12 km. Concentrations of ~200 μg m(-3) were identified by AVOID at distances from ~20 km to ~70 km. For the first time, airborne remote detection of volcanic ash has been successfully demonstrated from a long-range flight test aircraft.
Thermoelectric generators (TEGs) have the ability to convert waste heat into electrical energy under unfavorable conditions and are becoming increasingly popular in academia, but have not yet achieved a broad commercial success, due to the still comparably low efficiency. To increase the efficiency and economic viability of TEGs, research is performed on the materials on one hand and on the system connection on the other. In the latter case, the net output power of the cooling system plays a key role. At first glance, passive cooling seems preferable to active cooling because it does not affect the net electrical output power. However, as shown in the present review, the active cooling is to be preferred for net output power. The situation is similar in air and water-cooling. Even though air-cooling is easier to set up, the water-cooling should be preferred to achieve higher net output power. It is shown that microchannel cooling has similar hydraulic performance to conventional cooling and inserts increase the net output power of TEG. As the review reveals that active water-cooling should be the method of choice to achieve high net output power, it also shows that a careful optimization is necessary to exploit the potential.
Energiewirtschaft
(2007)