Location-oriented coordination in pervasive environments for collaborative work scenarios

Mobile or pervasive environments are inherently characterised by a high degree of dynamics and frequent changes in the environmental properties. This makes collaborative work of mobile users eminently difficult as the coordination of their work processes needs to adapt steadily to these changing circumstances. As location is one of the most critical changing context dimensions, this adaptive coordination and subsequent re-orientation are mostly based on distinctive temporal and spatial objects (the so-called Schelling points). The contribution of this article is to show the benefit of exploiting the human behaviour of using spatial objects for coordination (which we refer to as location-oriented coordination). We present an approach for which we implemented the location-oriented coordination considerations as a coordination pattern embedded in a coordination architecture, which serves as a runtime environment. By adopting this approach in a representative collaborative work scenario (in the domain of emergency management) and by presenting results from user tests we show its applicability and benefit.     

On‐Substrate Preparation of an Electroactive Conjugated Polyazomethine from Solution‐Processable Monomers and its Application in Electrochromic Devices

An electroactive polyazomethine is prepared from a solution processable 2,5‐diaminothiophene derivative and 4,4′‐triphenylamine dialdehyde by spray‐coating the monomers on substrates, including indium tin oxide (ITO) coated glass and native glass slides. The conjugated polymer was rapidly formed in situ by heating the substrates at 120 °C for 30 min in an acid saturated atmosphere. The resulting immobilized polymer is easily purified by rinsing the substrate with dichloromethane. The on‐substrate polymerization is tolerant towards large stoichiometry imbalances of the comonomers, unlike solution step‐growth polymerization. The resulting polyazomethine is electroactive and it can be switched reversibly between its neutral and oxidized states both electrochemically and chemically without degradation. A transmissive electrochromic device is fabricated from the immobilized polyazomethine on an ITO electrode. The resulting device is successfully cycled between its oxidized (dark blue) and neutral (cyan/light green) states with applied biases of +3.2 and ‐1.5 V under ambient conditions without significant color fatigue or polymer degradation. The coloration efficiency of the oxidized state at 690 nm is 102 cm² C^?1.     

Series resistance in organic bulk-heterojunction solar devices: Modulating carrier transport with fullerene electron traps

Series resistance is one of the key parameters affecting the performance of organic photovoltaic devices. Several electronic mechanisms arising from different structures within the solar cell can contribute to increasing it. We focus on the series resistance origin by altering the acceptor transport properties trough the incorporation of fullerene traps located at energies below the transporting electron levels. Indene-C₆₀ bisadduct as acceptor molecule blended with poly(3-hexylthiophene) forms the active layer in which small amounts of [6,6]-phenyl-C₆₁-butyric acid methyl ester have been added as trapping sites. A complete analysis of the impedance response has allowed identifying bulk transport resistive circuit elements in the high-frequency part of the spectra. Series resistance is observed to be dependent on the concentration of fullerene traps, thus indicating a connection between bulk transport processes and resistive elements. By comparing different contacts it has been discarded that outer cathode interfaces influence the series resistance experimentally extracted from impedance spectroscopy.     

Incompatible Length Scales in Nanostructured Cu2O Solar Cells

Electrodeposited Cu₂O‐ZnO heterojunctions are promising low‐cost solar cells. While nanostructured architectures improve charge collection in these devices, low open‐circuit voltages result. Bilayer and nanowire Cu₂O‐ZnO heterojunction architectures are systematically studied as a function of the Cu₂O layer thickness, ZnO nanowire length, and nanowire seed layer. It is shown that a thick depletion layer exists in the Cu₂O layer of bilayer devices, owing to the low carrier density of electrodeposited Cu₂O, such that the predominant charge transport mechanisms in the Cu₂O and ZnO are drift and diffusion, respectively. This suggests that the low open‐circuit voltage of the nanowire cells is due to an incompatibility between the nanostructure spacing required for good charge collection (<1 μm) and the heterojunction thickness necessary to form the full built‐in potential that inhibits recombination (>2 μm). The work shows the way to improve low‐cost Cu₂O cells: increasing the carrier concentration or mobility in Cu₂O synthesized at low temperatures.     

Acceptance‐Diffusion Strategies for Tablet‐PCs: Focused on Acceptance Factors of Non‐Users and Satisfaction Factors of Users

Among emerging devices propelling the growth of mobile devices, smartphones and tablet‐PCs are among the most recognizable. In this study, a research model is designed for exploring acceptance‐diffusion strategies for tablet‐PCs from the viewpoint of consumer perception, which is verified through a survey. The results of this study show that tablet‐PCs have great potential to be versatile, multifunctional devices, even though they are currently considered mostly as entertainment‐oriented rather than fulfilling the essential needs of everyday life. An analysis of the acceptance model for tablet‐PCs revealed that playability, cost level, functionality, and complexity significantly affect user acceptance. An analysis of the diffusion model, on the other hand, showed that playability and user interface have a significant influence on satisfaction, trust, and positive behavioral intention. We also found that cost level is not a major hindrance in the market diffusion of tablet‐PCs. The results of this study can be used to establish effective acceptance and diffusion strategies for tablet‐PCs and other emerging devices.