Damage effects of adhesives in modern glass façades: a micro-mechanically motivated volumetric damage model for poro-hyperelastic materials

This paper presents a micro-mechanically motivated volumetric damage model accounting for cavitation effects in modern glass connections, e.g. laminated glass connections. The volumetric part of an arbitrary Helmholtz free energy function is equipped with an isotropic damage formulation. To develop a micro-mechanical damage model, the porous micro-structure of a transparent structural silicone adhesive is analyzed numerically applying hydrostatic loading conditions. Based on the structural responses of different types of cubic representative volume elements incorporating an initial void fraction, three damage parameters are fitted utilizing the Levenberg–Marquard algorithm. The present volumetric damage model is implemented into ANSYS FE Code using a UserMat subroutine, where the algorithmic setting is described in detail in the present paper. To compare the structural responses of cubic equivalent homogeneous materials with representative volume elements, benchmark tests under hydrostatic loading are performed. The results indicate that the novel damage model accounts adequately for volumetric damage due to the cavitation effect. A special form of the pancake test is described briefly. The test allows for visualizing the cavitation effect during experimental testing. The experimental results of the pancake test are compared with numerical results, where the pancake test is simulated incorporating the micro-mechanical damage model. The micro-mechanically motivated scalar, internal damage variable is equipped with the obtained damage parameters from the structural response of the representative volume elements. The results show an adequate approximation of the experiment through the simulation. However, to optimize the results of the simulation, an optimization study on the damage parameters is conducted utilizing the Downhill-Simplex algorithm. Using the optimized damage parameters, the simulation of the pancake tests is further improved. Hence, it is shown that the novel micro-mechanically motivated volumetric damage model is excellently suited to represent the cavitation effect in poro-hyperelastic materials.     

Modelling the dynamics of landscape transformations and population growth in the highlands of Ethiopia using remote-sensing data

This study models landscape transformations and settlement dynamics in a highland area of Ethiopia over a 56 year period (1957–2013). The analyses were performed using aerial photographs, satellite images, and field data. The remotely sensed images were geometrically and radiometrically corrected. Visual interpretation of aerial photographs and supervised classification of multispectral satellite images using the maximum likelihood algorithm were chosen for land-cover mapping. The population size was estimated by counting the houses on the aerial photographs and on the high-resolution images, and by direct census. The overall trend showed an increase of cropland and a decrease of other types of land cover. Landscape transformation rates recently slowed down due to ownership and policy restrictions. The average cropland holding size per family has decreased from 2.6 to 1.1 ha due to the exponential growth of the population. The relationship between settlement and cropland expansion is statistically significant. Models of logistic growth were fitted to the cropland area, and models of exponential and logistic growth to the population development to estimate the carrying capacity. The concomitant increase of population and the decrease of cropland per head resulted in a shortage of food and energy, highlighting the importance of policy decisions on land management.     

Contract automata

Deontic logic as a way of formally reasoning about norms, an important area in AI and law, has traditionally concerned itself about formalising provisions of general statutes. Despite the long history of deontic logic, given the wide scope of the logic, it is difficult, if not impossible, to formalise all these notions in a single formalism, and there are still ongoing debates on appropriate semantics for deontic modalities in different contexts. In this paper, we restrict our attention to contracts between interactive parties, which are both general enough to be an interesting object of study but specific enough so as to narrow down the debates regarding the meaning of modalities, and present a formalism for reasoning about them.     

Electrical Detection and Magnetic Imaging of Stabilized Magnetic Skyrmions in Fe1−xCoxGe (x < 0.1) Microplates

Magnetic skyrmions are topologically protected spin textures that are being investigated for their potential use in next generation magnetic storage devices. Here, magnetic skyrmions and other magnetic phases in Fe_1?xCo_xGe (x < 0.1) microplates (MPLs) newly synthesized via chemical vapor deposition are studied using both magnetic imaging and transport measurements. Lorentz transmission electron microscopy reveals a stabilized magnetic skyrmion phase near room temperature (≈280 K) and a quenched metastable skyrmion lattice via field cooling. Magnetoresistance (MR) measurements in three different configurations reveal a unique anomalous MR signal at temperatures below 200 K and two distinct field dependent magnetic transitions. The topological Hall effect (THE), known as the electronic signature of magnetic skyrmion phase, is detected for the first time in a Fe_1?xCo_xGe nanostructure, with a large and positive peak THE resistivity of ≈32 nΩ cm at 260 K. This large magnitude is attributed to both nanostructuring and decreased carrier concentrations due to Co alloying of the Fe_1?xCo_xGe MPL. A consistent magnetic phase diagram summarized from both the magnetic imaging and transport measurements shows that the magnetic skyrmions are stabilized in Fe_1?xCo_xGe MPLs compared to bulk materials. This study lays the foundation for future skyrmion‐based nanodevices in information storage technologies.     

Semantics in space systems architectures

Costs, life cycles, technologies and agreements between stakeholders and organizations make space systems unique with respect to the complexity. A commonly accepted technique to address part of this complexity is to model and to maintain space systems architectures through the life cycle of their space programs. The benefits may range from supporting consistent model definitions and maintenance up to supporting analysis and verification. Space systems architectures have been modeled using UPDM (unified profile for DoDAF And MODAF; a UML profile). In fact, UPDM argues that it provides a clearer understanding of the semantics behind specific views and viewpoints. Nonetheless, while UML defines its semantics imprecisely using plain text and variation points, UPDM does not define any semantics. In this paper, we evaluate an extension of fUML (semantics of a foundational subset for executable UML models) as a semantics for space systems architectures. The extension of fUML as a synchronous language (synchronous fUML) provides a limited, but formally precise and deterministic, form to describe structure and behavior in UML. Through the combination of this semantics with UPDM, a precise language supporting a standardized meta-model emerges for the definition of space systems architectures. At the end, a simplified case study covering the operational view (OV-*) is presented. Our initial results show that synchronous fUML is able to offer a precise and deterministic semantics for UPDM.     

Dezentrale Aufbereitung und Lagerung von Speiseresten – Neue Wege zur Ressourcen- und Energiespeicherung

Organic waste, especially kitchen and canteen waste, is produced in large quantities and is subject to considerable fluctuations, both in terms of its composition and quantity, due in part to changing seasonal factors. Kitchen waste commonly undergoes biological and primarily anaerobic waste treatment (fermentation), producing both material (digestate, fertilizers and soil conditioners) and energy resources (biogas, electrical and thermal energy). The introduction of decentral collection and treatment systems promises to offer new solutions with regard to resource and energy storage, and with regard to compensating for the previously mentioned fluctuations. Within this study kitchen waste was initially pretreated and processed at laboratory scale. Subsequently, the influence of storage at 5, 20 and 30?°C for a period of 28 days was investigated. It was determined that, when stored, acidification and a corresponding drop in pH value promptly set in. The higher the temperature, the higher the level of acidification and the higher the concentration of organic acids became. In order to analyze the effects of storage on kitchen waste as an energy source, its biogas potential was measured in correlation with storage duration and temperature. Neither factor proved to have any significant influence on gas yield. Due to acidification, which can be seen as a chemical decomposition process, stored substrates produced up to 20?% higher gas yield compared to the original substrate. Accordingly, unavoidable kitchen and canteen waste can be considered valuable energy sources, which can contribute to efficient and needs-oriented energy production.     

Simulations and experimental investigation of paint film leveling

The surface structure of a paint film is the result of the interplay of a variety of physical influences, e.g., the superposition of droplets during spray application, the surface tension-driven leveling, and the viscosity increase in the leveling phase. A numerical simulation program is presented that incorporates all the relevant mechanisms of paint film structure formation during and after spray application. The simulation program was validated by comparing simulations and leveling experiments. The influence of the initial film geometry and viscosity on the leveling behavior is demonstrated. For the investigations, model liquids and commercial paints with an increasing complexity of the physical properties were chosen: Newtonian flow behavior without solvent evaporation, Newtonian flow behavior with solvent evaporation, viscoelastic paints with non-Newtonian flow behavior. Four variants are proposed regarding how thixotropy can be measured and how a mathematical model can be created. The advantages and disadvantages of the variants with regard to the implementation of thixotropy in the simulations are listed. A method to predict the leveling behavior of thixotropic paints with simultaneous recovery of the viscous and elastic properties from rheological measurements using discrete relaxation time spectra is presented.     

NOx Reduction over CeO2–ZrO2 Supported Iridium Catalyst in the Presence of Propanol

The 1-propanol assisted-reduction of NO _x was investigated over Ir/Ce_0.6Zr_0.4O₂. The catalytic performances of such a catalyst, the associated FTIR characterizations, and transient experiments suggest the formation of adsorbed R-NO _x species as intermediates of the deNO _x process; they provide the partially oxidized species required by the deNO _x model.     

Electrochemical characterization of radiation-grafted ion-exchange membranes based on different matrix polymers

Seven proton conducting membranes based on different commercial fluoropolymer films were prepared by radiation grafting with styrene followed by sulfonation. These membranes were studied as candidates for fuel cell electrolyte membranes and compared to Nafion^® 105 and 117 with respect to conductivity, oxygen and hydrogen permeability, kinetics of the oxygen reduction reaction (ORR) and performance in a fuel cell. The dependence of the conductivity of the membranes on the relative humidity (RH) and temperature was also determined. The conductivity was observed to depend on the membrane thickness and the water uptake. The dependence of the conductivity on the temperature and the RH was the same for all of the experimental membranes. Reactant gas permeabilities appeared to depend only slightly on the matrix material and no major differences in the Tafel slopes and exchange current densities of the ORR were observed. Membranes with high water uptakes appeared to be less durable in the fuel cell than membranes with low water uptakes. Thus to prepare a membrane that is durable under the fuel cell conditions, the water uptake must remain low even at the expense of the conductivity.     

Value and worthlessness of clinical studies in the diagnosis of brain death

Death was ever determined on the basis of extinguished partial functions of the entire organism (partial death). In intensive medicine with its possibilities of reanimation, with its possibilities of artificial maintenance of breathing and circulation the individual death of man is equated with his cerebral death. It comes only under conditions of reanimation and nearly always shows a clinically recognizable development. Practically above all "the syndromes in the forefield of cerebral death" are of interest as well as its obligatory and optional symptoms, the valency of which was critically tested. A 5-year-analysis (1969 to 1973) of 487 deaths in an internal intensive therapy unit (18% of mortality) was shown that causes, frequency and age distribution of the mortal conditions of disease as well as the average survival time of 4.5 days, in which cases, however, 43% of all deaths occurred within the first 24 hours, very rarely caused us to establish the irreversibility of the loss of the cerebral function on account of an organic dysfunction, but rather resulting from the question of the interruption of an absurd reanimation.