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Wärme: Zuverlässige Kollektoren liefern hohe Solarerträge: Monitoring von Solarthermieanlagen
(2017)
There is a popular saying in German: Innovation is when the market shouts “Hooray!”. Thus, a new idea is only as good as its diffusion into the addressed social system. The question is what affects the adoption or rejection of a new idea. Carsten Deckert shares his experience on the main innovation resistances and on ways to increase the acceptance of new ideas. He talks about which perceived attributes of innovations are conducive to the rate of adoption of an innovation and which are characteristics of failed innovations.
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.
Innovative thinking opens up new growth prospects in mechanical and plant engineering. Mechanical and plant engineering has been traditionally very important to the industrial location of Germany [1]. With an export share of 70%, it has a considerable direct influence on economic structure and job market. In addition, mechanical engineering is the “innovation engine” for other core industries in Germany – as supplier of production equipment for industries such as the car manufacture, plastics processing and electrical engineering sectors. Only through this production equipment can innovative products reach production readiness in the first place, and can “Made in Germany” continue to enjoy an excellent reputation all over the world.
Vitaler Wissensaustausch
(2008)
Schätzungen zufolge besitzen ein Viertel bis ein Drittel der Mitarbeiter eines Unternehmens unverzichtbares Experten-Know-how. Keine Organisation kann es sich heutzutage leisten, dieses Wissen nicht oder auch nur unvollständig zu nutzen. Darüber hinaus führt der demografische Wandel in Deutschland dazu, dass dieses Wissen den Unternehmen zunehmend verloren geht, wenn sie keinen vitalen Wissensaustausch betreiben.
Vergleichende Untersuchung von Kesseleinbindungen in solarthermischen Kombianlagen. Posterbeitrag
(2012)
In dieser Arbeit wird ein allgemeingültiges Verfahren zur Tragfähigkeitsberechnung von hochübersetzenden Epizykloidengetrieben entwickelt. Epizykloidengetriebe sind spezielle Umlaufrädergetriebe mit epizykloidaler Triebstockverzahnung. Die Grundlage des Verfahrens bilden die Berechnungs- und Anwendungsnormen der DIN 3990. Neben der Herleitung des Rechengangs wird beispielhaft der Tragfähigkeitsnachweis für die Anwendung in einem urbanen Elektrofahrzeug ausgeführt. Das dabei betrachtete Epizykloidengetriebe hat eine Übersetzung von -34 bei einer maximalen Eingangsdrehzahl von 20.000 min-1 und einer zu übertragenden Leistung von 27 kW. Der Rechengang teilt sich auf in den Nachweis der Flankentragfähigkeit, der Zahnfußtragfähigkeit und der Fresstragfähigkeit. Das Vorgehen je Nachweis ist dabei vergleichbar: Es werden zunächst individuelle Faktoren berechnet, die anschließend in den rechnerischen Festigkeitsnachweis einfließen. Bei der Entwicklung des Rechenverfahrens wird auf eine Allgemeingültigkeit der Gleichungen geachtet. Damit wird die erstellte Auslegungsgrundlage auch für ein breites Einsatzspektrum außerhalb der Elektromobilität nutzbar. Für zukünftige Untersuchungen zu Aspekten der Dimensionierung und Anwendung der Epizykloidengetriebe werden Hinweise und Ansätze basierend auf den erlangten Erkenntnissen bereitgestellt.
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.
The synthesis of Nb-doped TiO2 nanoparticles by spray drying: an efficient and scalable method
(2011)
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.
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.
A central question for managers in charge of innovation is to what extent creativity and inno-vation can be controlled and supervised, or whether they just have to be set free and allowed to take shape. In assessing this dilemma the authors conclude that there is a contradiction of action versus inaction on the personal level as well as a contradiction of control versus loss of control on the organizational level. What European innovators can learn from philosophical Daoism is an attitude that allows a process to just develop “naturally” and refrains from prem-ature interference with the intention to permanently be in control. In business structures that judge everything according to its usefulness, i.e. profitability for the company, a look at the laid-back attitude of Daoism where usefulness and uselessness are relative qualities might relief the pressure on people to perform in a premeditated way. Innovation can be supported, but creativity cannot be forced. It can only be allowed to happen when control, interference, and action are balanced out with non-interference, and go-with-the-flow. This attitude in not an excuse for stressed-out managers to neglect their duty, but a time honoured worldview of one of the oldest civilizations in the world that can give them the sovereignty to “get out of the way” and let innovation happen.
This paper explores the tensions in team creativity. The tensions in team creativity are based on a tension between originality and effectiveness in the standard definition of creativity. To display the tensions in team creativity, the value square (“Wertequadrat”) developed by Schulz von Thun (1998) is used which balances a value with its countervalue. The author identifies tensions for cohesion, consensus and conformity. Cohesion is described as a tension between team diversity and team safety, consensus as a tension between constructive controversy and participatory decision-making and conformity as a tension between support for innovation and task orientation. Finally, the connection of individual and team creativity is described as an interplay between solitary and interactive components.
The definition of individual creativity is based on a tension between novelty on the one side and usefulness respectively appropriateness on the other side. The paper explores how this tension pervades the stage and componential theories of creativity. To achieve this, the so called value square (“Wertequadrat”) developed by Helwig (1967) and Schulz von Thun (1998)is used which balances a value with its countervalue to analyze creativity. The author identifies tensions of action and inaction, expertise and mindfulness, precision and ambiguity as well as immersion and detachment permeating the creative process and the components of creativity. As a conclusion a morphological box for creativity is presented which allows one to show which combination of characteristics of the tensions support different stages of creativity. Furthermore implications for development and time management are discussed.
The standard definition of creativity is based on a tension between originality and effectiveness. Borrowing from the wave-particle duality in physics one could say that there is an originality-effectiveness duality at work for creativity. The paper explores how this tension pervades Amabile's (1997) componential theory of organizational creativity with the components organizational motivation, management practices (including work assignment and work control) and resources. As a method the so called value square (" Wertequadrat ") developed by Helwig (1967) and Schulz von Thun (1998) is used which balances a value with its countervalue. The author identifies a tension of corporate tradition and corporate change for organizational motivation, a tension of skills and challenges for work assignment, a tension of management by control and management by loss of control for work control as well as a tension of organizational efficiency and organizational slack for resources. Additionally different implications of these tensions for the resistance of a company to creativity, for an organizational climate conducive to creativity as well as for resource allocation in creative endeavours are discussed.
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.
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.
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.
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.
Synthesis and Analysis of a Novel Linkage Mechanism with the Helical Motion of the End-Effector
(2020)
In the present contribution, the utilization of steel-mill gases for an industrial methanol synthesis process is described. The focus of this work is on the influence of syngas compositions derived from steel-mill gases on an industrial Cu/ZnO/Al2O3 catalyst. Elevated CO2 and H2O concentrations seem to have an irreversible impact on the activity of the catalyst. In order to obtain realistic gas composition for the catalyst tests, a process simulation of the methanol synthesis was conducted. The calculated gas compositions at the reactor inlet were applied in a practical test in order to evaluate the catalyst stability under steel mill gas conditions. No noticeable deactivation was observed.
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.
The optimization of full-scale biogas plant operation is of great importance to make biomass a competitive source of renewable energy. The implementation of innovative control and optimization algorithms, such as Nonlinear Model Predictive Control, requires an online estimation of operating states of biogas plants. This state estimation allows for optimal control and operating decisions according to the actual state of a plant. In this paper such a state estimator is developed using a calibrated simulation model of a full-scale biogas plant, which is based on the Anaerobic Digestion Model No.1. The use of advanced pattern recognition methods shows that model states can be predicted from basic online measurements such as biogas production, CH4 and CO2 content in the biogas, pH value and substrate feed volume of known substrates. The machine learning methods used are trained and evaluated using synthetic data created with the biogas plant model simulating over a wide range of possible plant operating regions. Results show that the operating state vector of the modelled anaerobic digestion process can be predicted with an overall accuracy of about 90%. This facilitates the application of state-based optimization and control algorithms on full-scale biogas plants and therefore fosters the production of eco-friendly energy from biomass.
Dieser Beitrag untersucht die Spannungsfelder der Teamkreativität. Die Spannungsfelder basieren auf einer grundlegenden Spannung aus Originalität und Effektivität, die der Standarddefinition der Kreativität zugrunde liegt. Es lassen sich auf Basis des Teamklimas und -kontextes Spannungsfelder hinsichtlich Konformität, Konsens und Kohäsion identifizieren. Mit Bezug zur Konformität müssen Teams ein positives Spannungsfeld aus der Unterstützung für Innovation und Aufgabenorientierung erreichen, um gleichzeitig Experimentierfreude zu fördern und hohe Qualitätsansprüche zu erzielen. Konsens entsteht im Spannungsfeld aus konstruktivem Konflikt und partizipatorischer Entscheidungsfindung. Bei der Kohäsion besteht eine Spannung zwischen der Teamidentität (Geborgenheit) und den individuellen Identitäten der Teammitglieder (Diversität). Der Beitrag beschreibt, wie diese drei Spannungsfelder zusammenarbeiten, wenn außergewöhnliche Kreativität in Teams entsteht.
Die Definition der individuellen Kreativität basiert auf einem fundamentalen Spannungsverhältnis zwischen Neuartigkeit und Originalität auf der einen Seite sowie Nützlichkeit und Angemessenheit auf der anderen Seite. Man kann in Anlehnung an den Welle-Teilchen-Dualismus des Lichtes auch von einem Originalitäts-Effektivitäts-Dualismus der Kreativität sprechen. Diese zweiteilige Serie betrachtet die Auswirkungen dieses Spannungsverhältnisses auf den kreativen Prozess und die Komponenten der Kreativität. Im ersten Teil wurde bereits das Spannungsverhältnis des kreativen Prozesses aus Handeln und Geschehen-Lassen betrachtet. In diesem Beitrag werden die Spannungsfelder der Komponenten der Kreativität nach Amabile behandelt: Expertise, kreatives Denken und Motivation. Zur Darstellung dieser Sachverhalte wird das Wertequadrat nach Helwig und Schulz von Thun verwendet, in dem ein Wert ins Verhältnis mit seinem positiven Gegenwert gesetzt wird. Dadurch können bzgl. der Komponenten der Kreativität Verbesserungsmaßnahmen abgeleitet und ein morphologischer Kasten der Kreativität aufgestellt werden.
Die Definition der individuellen Kreativität basiert auf einem fundamentalen Spannungsverhältnis zwischen Neuartigkeit und Originalität auf der einen Seite sowie Nützlichkeit und Angemessenheit auf der anderen Seite. Man kann in Anlehnung an den Welle-Teilchen-Dualismus des Lichtes auch von einem Originalitäts-Effektivitäts-Dualismus der Kreativität sprechen. Diese zweiteilige Serie betrachtet die Auswirkungen dieses Spannungsverhältnisses auf den kreativen Prozess und die Komponenten der Kreativität. In diesem ersten Teil wird das Spannungsverhältnis des kreativen Prozesses aus Handeln und Geschehen-Lassen betrachtet. In der nächsten Ausgabe folgt ein Beitrag über die Spannungsfelder der Komponenten der Kreativität nach Amabile: Expertise, kreative Denkfertigkeiten und Motivation. Zur Darstellung dieser Sachverhalte wird das Wertequadrat nach Helwig (1967) und Schulz von Thun (1998) verwendet, in dem ein Wert ins Verhältnis mit seinem positiven Gegenwert gesetzt wird. Dadurch können bzgl. des kreativen Prozesses die negativen Auswirkungen operativer Hektik in Form einer „Culture of Looking Busy“ und Implikationen für das individuelle Zeitmanagement abgeleitet werden.