Failed solutions to the energy crises: nuclear power, coal conversion, and the chemical industry in West Germany since the 1960s

By the end of the economic boom in the 1960s, the oil crisis caused an enormous rise in energy prices. Chemical companies, especially, faced a huge challenge due to their dependency on oil as an energy resource and raw material. This paper explores the reaction of West German chemical corporations to the energy crises of the 1970s and their attempts to anticipate future energy crises. First, the companies tried to implement their own industrial nuclear power stations to cut costs and to become more independent from oil. Second, and with the help of the social-liberal government, they attempted to revive coal conversion technology

New asymptotic heat transfer model in thin liquid films

In this article, we present a model of heat transfer occurring through a li\-quid film flowing down a vertical wall. This new model is formally derived using the method of asymptotic expansions by introducing appropriately chosen dimensionless variables. In our study the small parameter, known as the film parameter, is chosen as the ratio of the flow depth to the characteristic wavelength. A new Nusselt solution should be explained, taking into account the hydrodynamic free surface variations and the contributions of the higher order terms coming from temperature variation effects. Comparisons are made with numerical solutions of the full Fourier equations in a steady state frame. The flow and heat transfer are coupled through Marangoni and temperature dependent viscosity effects. Even if these effects have been considered separately before, here a fully coupled model is proposed. Another novelty consists in the asymptotic approach in contrast to the weighted residual approach which have been formerly applied to these problems.Comment: 28 pages, 6 figures, 39 references. Other author's papers can be downloaded at http://www.denys-dutykh.com

Anticoagulant and Antiplatelet Therapy in Patients with Atrial Fibrillation and Coronary Artery Disease

Anticoagulation represents the mainstay of therapy for most patients with atrial fibrillation. Patients on oral anticoagulation often require concomitant antiplatelet therapy, mostly because of coronary artery disease. After coronary stent implantation, dual antiplatelet therapy is necessary. However, the combination of oral anticoagulation and antiplatelet therapy increases the bleeding risk. Risk scores such as the CHA2DS2-Vasc score and the HAS-BLED score help to identify both bleeding and stroke risk in individual patients. The guidelines of the European Society of Cardiology provide a rather detailed recommendation for patients on oral anticoagulation after coronary stent implantation. However, robust evidence is lacking for some of the recommendations, and especially for new oral anticoagulants and new antiplatelets few or no data are available. This review addresses some of the critical points of the guidelines and discusses potential advantages of new anticoagulants in patients with atrial fibrillation after stent implantation

Sense-Giving Strategies of Media Organisations in Social Media Disaster Communication: Findings from Hurricane Harvey

Media organisations are essential communication stakeholders in social media disaster communication during extreme events. They perform gatekeeper and amplification roles which are crucial for collective sense-making processes. In that capacity, media organisations distribute information through social media, use it as a source of information, and share such information across different channels. Yet, little is known about the role of media organisations on social media as supposed sense-givers to effectively support the creation of mutual sense. This study investigates the communication strategies of media organisations in extreme events. To that matter, a Twitter dataset consisting of 9,414,463 postings was collected during Hurricane Harvey in 2017. We employed social network analysis and content analysis methods to identify media communication approaches. Three different sense-giving strategies were identified: retweeting local in-house outlets; bound amplification of messages of individual associated journalists; and open message amplification

How microscopic stress and strain analysis can improve the understanding of the interplay between material properties and variable amplitude fatigue

Lightweight construction is one of the most demanded technologies in many engineering systems. In order to guarantee the safety of the whole system, it is mandatory to improve models that describe and predict its behavior under load. Fatigue, the damaging of materials under cyclic loading, is the main phenomenon leading to failure in e.g. automobile and aerospace components. Cyclic loading during service does usually not happen with constants amplitudes, rather there are complex patterns of different load levels. High load variations in these patterns lead to deviations from the linear Paris behavior. Strong decelerations occur as consequence of a single increased tensile load, which is known as the overload effect. Nevertheless, this effect does not affect all materials the same, there are materials that show a strong overload sensitivity and others on which overloads only have a minor influence. Reasons for this can be seen in the interplay of the underlying mechanisms of the overload effect: plasticity induced crack closure and compressive residual stresses. While both effects lead to crack tip shielding and a reduction of stress intensity, crack closure delays the opening of the crack tip and thereby reduces the effective ΔK range, whereas compressive residual stresses superimpose with crack tip stresses and thereby reduce Kmax. Possible reasons for differences in the sensitivity can be differences in the strain hardening, both in the static and in the dynamic case, as well as in changes of the sign of stresses (Bauschinger effect). Since crack propagation is driven by local stresses and strains, measurements to examine differences in them have to be performed on a microscopic scale. We could show that by the combination of modern measurement techniques – magnetic Barkhausen noise and digital image correlation in scanning electron microscope – we were able to image, separate and evaluate the mechanisms of the overload effect quantitatively. The calibrated magnetic Barkhausen noise microscope allows us measurements of residual stresses with a spatial resolution of 10 µm. From the digital image correlation results we could evaluate the crack tip driving forces namely the crack opening behavior, changes in the stress intensity Kand in the strain energy release rate via the J-integral. Using a simple model based on these results, we were furthermore able to predict the crack growth behavior due to the overload effect. These results will be used to extend crack growth models, while taking the interaction of materials´ properties with the mentioned mechanisms into account. This should enable a physically based, improved lifetime prediction and material selection for certain load patterns

How microscopic stress and strain analysis can improve the understanding of the interplay between material properties and variable amplitude fatigue

Lightweight construction is one of the most demanded technologies in many engineering systems. In order to guarantee the safety of the whole system, it is mandatory to improve models that describe and predict its behavior under load. Fatigue, the damaging of materials under cyclic loading, is the main phenomenon leading to failure in e.g. automobile and aerospace components. Cyclic loading during service does usually not happen with constants amplitudes, rather there are complex patterns of different load levels. High load variations in these patterns lead to deviations from the linear Paris behavior. Strong decelerations occur as consequence of a single increased tensile load, which is known as the overload effect. Nevertheless, this effect does not affect all materials the same, there are materials that show a strong overload sensitivity and others on which overloads only have a minor influence. Reasons for this can be seen in the interplay of the underlying mechanisms of the overload effect: plasticity induced crack closure and compressive residual stresses. While both effects lead to crack tip shielding and a reduction of stress intensity, crack closure delays the opening of the crack tip and thereby reduces the effective ΔK range, whereas compressive residual stresses superimpose with crack tip stresses and thereby reduce Kmax. Possible reasons for differences in the sensitivity can be differences in the strain hardening, both in the static and in the dynamic case, as well as in changes of the sign of stresses (Bauschinger effect). Since crack propagation is driven by local stresses and strains, measurements to examine differences in them have to be performed on a microscopic scale. We could show that by the combination of modern measurement techniques – magnetic Barkhausen noise and digital image correlation in scanning electron microscope – we were able to image, separate and evaluate the mechanisms of the overload effect quantitatively. The calibrated magnetic Barkhausen noise microscope allows us measurements of residual stresses with a spatial resolution of 10 µm. From the digital image correlation results we could evaluate the crack tip driving forces namely the crack opening behavior, changes in the stress intensity Kand in the strain energy release rate via the J-integral. Using a simple model based on these results, we were furthermore able to predict the crack growth behavior due to the overload effect. These results will be used to extend crack growth models, while taking the interaction of materials´ properties with the mentioned mechanisms into account. This should enable a physically based, improved lifetime prediction and material selection for certain load patterns