Thermodynamic modeling of the Na–Al–Ti–H system and Ti dissolution in sodium alanates

Thermodynamic assessments were made to optimize thermodynamic models and parameter fits to selected experimental and first principles hypothetical predicted phase data within the Na–Al–Ti–H system. This enabled thermodynamic modeling of Ti solubility within the sodium alanates: NaAlH₄ and Na₃AlH₆, and the relative stability of Ti-bearing phases. The modeling provides insights into the role of Ti originating from Ti-based activating agents commonly referred to as ‘catalysts’ in promoting reversibility of the Na–Al–H dehydrogenation and rehydrogenation reactions under moderate temperature and pressure conditions relevant to H storage applications. Preliminary assessments were made to evaluate H solubility in bcc-Ti and hcp-Ti, and stability of the hydride δ-TiH₂. To model possible Ti dissolution in NaAlH₄ and α-Na₃AlH₆, sub-lattice models were applied. A repulsive interaction is predicted by first principles calculations when Ti is dissolved in NaAlH₄ or α-Na₃AlH₆, which becomes stronger with increasing temperature. Although Ti is virtually insoluble in NaAlH₄ or α-Na₃AlH₆, a small addition of TiCl₃ will induce a thermodynamic driving force for formation of TiH₂ and/or TiAl₃. The addition of pure Ti shows a weaker effect than TiCl₃ and leads to formation of TiH₂ only. Based on a combined interpretation of present thermodynamic modeling and prior experimental observations, the TiAl₃ and TiH₂ phases are ascribed to have a catalytic effect, not a thermodynamic destabilization effect, on the reversibility of the dehydrogenation/rehydrogenation reactions in the Na–Al–H system.     

The process map as an instrument to standardize processes: design and application at a financial service provider

The standardization of processes and the identification of shared business services in a service-oriented architecture (SOA) are currently widely discussed. Above all in practice, however, there still is a lack of appropriate instruments to support these tasks. In this paper an approach for a process map is introduced which allows for a systematic presentation—as complete as possible—of the processes in an enterprise (division). After a consistent refinement of the process has taken place by means of aggregation/disaggregation respectively, generalization/specialization relations, it is possible to identify primarily functional similarities of the detailed sub-processes. The application of the process map at a financial service provider (FSP) highlights how these similarities can be taken as a basis to standardize processes and to identify shared services.     

Experimental quantification of annular dark-field images in scanning transmission electron microscopy

This paper reports on a method to obtain atomic resolution Z-contrast (high-angle annular dark-field) images with intensities normalized to the incident beam. The procedure bypasses the built-in signal processing hardware of the microscope to obtain the large dynamic range necessary for consecutive measurements of the incident beam and the intensities in the Z-contrast image. The method is also used to characterize the response of the annular dark-field detector output, including conditions that avoid saturation and result in a linear relationship between the electron flux reaching the detector and its output. We also characterize the uniformity of the detector response across its entire area and determine its size and shape, which are needed as input for image simulations. We present normalized intensity images of a SrTiO(3) single crystal as a function of thickness. Averaged, normalized atom column intensities and the background intensity are extracted from these images. The results from the approach developed here can be used for direct, quantitative comparisons with image simulations without any need for scaling.     

SO(3) nonlinear σ model for a spiral phase in the spin-fermion model

Starting from a doped spin-fermion model for the CuO₂ planes in high-T_c superconductors, we derive an effective continuum theory for the spin degrees of freedom by means of a gradient expansion. We assume an incommmensurate, spiral configuration for the spins. Extending our previous treatment of a planar spiral, we allow for three-dimensional fluctuations of the spin fields, which are described by an S0(3) matrix order parameter. The continuum limit is obtained by a systematic expansion in powers of a short distance cutoff. The occurring infinite series is summed to all orders using a combinatorial method which exploits the constraint obeyed by the S0(3) order parameter. The resulting continuum theory is given by an S0(3) quantum nonlinear model, where the influence of doping is contained in the fermionic susceptibilities that enter into the coupling constants of the model.     

Tuning the Intermolecular Electrostatic Interaction toward High-Efficiency and Low-Cost Organic Solar Cells

Organic solar cells (OSCs) have achieved much progress with rapidly increasing power conversion efficiencies (PCEs). It should be noted that the top-performance OSCs are generally consisted of active materials with complex chemical structures, resulting in high costs. Here, combining the material design and morphology control, high-efficiency OSCs are fabricated by a low-cost donor: acceptor blend. A completely non-fused electron acceptor named Tz is designed and synthesized via introducing thiazole units on both sides of a bithiophene core, which shows an outstanding PCE of 13.3% with a typical polythiophene donor. More importantly, optimization guidelines are presented to get excellent morphology for low-cost donor:acceptor systems. Three polythiophenes are selected, poly(3-hexylthiophene) and its two derivatives with electron-withdrawing substitutions (PDCBT and PDCBT-2F), as donors to fabricate the cell devices. The computational and experimental data reveal that decreasing the electrostatic interaction between polythiophene and Tz is the key to getting a suppressed miscibility and thus a high phase purity. This study provides insight into the molecular design and donor:acceptor matching requirements for high-efficiency and low-cost OSCs.     

Magnetic Properties of Thermal Sprayed Tungsten Carbide–Cobalt Coatings

In the information age, the storage and accessibility of data is of vital importance. There are several possibilities to fulfill this task. Magnetic storage of data is a well‐established method and the range of materials used is continuously extended. In this study, the magnetic remanence of thermally sprayed tungsten carbide–cobalt (WCCo)‐coatings in dependence of their thickness is examined. Two magnetic fields differing in value and geometry are imprinted into the coatings and the resulting remanence field is measured. It is found that there are two effects, which in combination determine the effective value of the magnetic remanence usable for magnetic data storage.

     

Service integrators in business networks—the importance of relationship values

To realise the potentials of CRM (customer relationship management), relationship-specific processes need to be designed and implemented in companies. This is all the more important and complicated in business networks where two or more actors collaborate to serve the customers. A good collaboration within business networks is the basis for understanding the customer process and identifying customer needs. But, even in these days of customer orientation, transaction orientation is still a matter of strong interest, and the following questions remain to be answered: What is the difference between relationship-oriented processes and transaction-oriented processes, and how can relationship-oriented processes be designed for a business network? The authors give first answers to both questions by using a systematic, goal-oriented specialisation of generic actions. To give an example, one relationship-oriented process will be designed and specified for a certain customer process in the course of this paper.     

Reading from computer screen versus reading from paper: does it still make a difference?

Four experiments were conducted to test whether recent developments in display technology would suffice to eliminate the well-known disadvantages in reading from screen as compared with paper. Proofreading speed and performance were equal for a TFT-LCD and a paper display, but there were more symptoms of eyestrain in the screen condition accompanied by a strong preference for paper (Experiment 1). These results were replicated using a longer reading duration (Experiment 2). Additional experiments were conducted to test hypotheses about the reasons for the higher amount of eyestrain associated with reading from screen. Reduced screen luminance did not change the pattern of results (Experiment 3), but positioning both displays in equal inclination angles eliminated the differences in eyestrain symptoms and increased proofreading speed in the screen condition (Experiment 4). A paper-like positioning of TFT-LCDs seems to enable unimpaired reading without evidence of increased physical strain.

Practitioner Summary: Given the developments in screen technology, a re-assessment of the differences in proofreading speed and performance, well-being, and preference between computer screen and paper was conducted. State-of-the-art TFT-LCDs enable unimpaired reading, but a book-like positioning of screens seems necessary to minimise eyestrain symptoms.     

The semigroups of linearly realizable finite automata. I

Summary First the problem is solved how one can decide whether an arbitrary finite semigroup H is linearly A-realizable, i.e., whether there exists a linearly realizable finite automaton having a semigroup isomorphic to H. This leads to a question about the existence of certain generating subsets of H. The determination of these subsets is rather complicated in case H-HH=Ø and very simple in case H-HH#Ø. But in the first case we are able to clear up completely the structure of the semigroups which are linearly A-realizable: These are exactly the finite right groups which have maximal subgroups of the type described by Ecker in [4]. In the second case we get only necessary structure conditions. Among other things we shall see: If a semigroup H is linearly A-realizable one can define a congruence relation on it having the property, that H is isomorphic to a semigroup of a strongly connected and linearly realizable automaton iff the so-called index of H equals the index of H/. Developing these results about semigroups we obtain at the same time many structure theorems about linearly realizable automata.     

User-centred process for the definition of free-hand gestures applied to controlling music playback

Music is a fundamental part of most cultures. Controlling music playback has commonly been used to demonstrate new interaction techniques and algorithms. In particular, controlling music playback has been used to demonstrate and evaluate gesture recognition algorithms. Previous work, however, used gestures that have been defined based on intuition, the developers’ preferences, and the respective algorithm’s capabilities. In this paper we propose a refined process for deriving gestures from constant user feedback. Using this process every result and design decision is validated in the subsequent step of the process. Therefore, comprehensive feedback can be collected from each of the conducted user studies. Along the process we develop a set of free-hand gestures for controlling music playback. The situational context is analysed to shape the usage scenario and derive an initial set of necessary functions. In a successive user study the set of functions is validated and proposals for gestures are collected from participants for each function. Two gesture sets containing static and dynamic gestures are derived and analysed in a comparative evaluation. The comparative evaluation shows the suitability of the identified gestures and allows further refinement. Our results indicate that the proposed process, that includes validation of each design decision, improves the final results. By using the process to identify gestures for controlling music playback we not only show that the refined process can successfully be applied, but we also provide a consistent gesture set that can serve as a realistic benchmark for gesture recognition algorithms.