Exploring pathways for sustainable water management in river deltas in a changing environment

Exploring adaptation pathways into an uncertain future can support decisionmaking in achieving sustainable water management in a changing environment. Our objective is to develop and test a method to identify such pathways by including dynamics from natural variability and the interaction between the water system and society. Present planning studies on long-term water management often use a few plausible futures for one or two projection years, ignoring the dynamic aspect of adaptation through the interaction between the water system and society. Our approach is to explore pathways using multiple realisations of transient scenarios with an Integrated Assessment Meta Model (IAMM). This paper presents the first application of the method using a hypothetical case study. The case study shows how to explore and evaluate adaptation pathways. With the pathways it is possible to identify opportunities, threats, timing and sequence of policy options, which can be used by policymakers to develop water management roadmaps into the future. By including the dynamics between the water system and society, the influence of uncertainties in both systems becomes clearer. The results show, among others, that climate variability rather than climate change appears to be important for taking decisions in water management

High sensitive quasi freestanding epitaxial graphene gassensor on 6H-SiC

We have measured the electrical response to NO$_2$, N$_2$, NH$_3$ and CO for epitaxial graphene and quasi freestanding epitaxial graphene on 6H-SiC substrates. Quasi freestanding epitaxial graphene shows a 6 fold increase in NO2 sensitivity compared to epitaxial graphene. Both samples show a sensitivity better than the experimentally limited 1 ppb. The strong increase in sensitivity of quasi freestanding epitaxial graphene can be explained by a Fermi-energy close to the Dirac Point leading to a strongly surface doping dependent sample resistance. Both sensors show a negligible sensitivity to N$_2$, NH$_3$ and CO

Vibrations of adsorbates on metal surfaces from geometry optimizations

We present a method to compute harmonic vibrations that uses the structures and the forces in the structures that are obtained from a geometry optimization. It does not require any additional electronic structure calculations. The method generally takes only on the order of minutes on a regular PC, but it does not guarantee the calculation of all vibrations of a system. Tests on small adsorbates on a transition metal surface show, however, that the most relevant vibrations are obtained. An important part of the method is the inclusion of several checks to determine the reliability of its results, which gives also error estimates of the vibrational frequencies

Toward a more sustainable coffee production

This paper contributes to the literature on the emerging trend of Southern sustainability standards and certifications as a reaction to the Northern-based private standards by businesses and NGOs. It particularly analyzes the implementation capacity of ISCoffee as a public standard and certification initiated by the Indonesian government. We analyze the opportunities and barriers in the process of implementing ISCoffee and examine whether ISCoffee can become a viable alternative to Northern-based private standards and certification. We first conclude that the implementation capacity of ISCoffee is low, because of weak administrative structures, and communication and coordination deficiencies. Second, we conclude that ISCoffee will unlikely being able to solve smallholder-related problems in the coffee sector such as limited access to market, insufficient capital, and underdeveloped farmer organizations. Finally, we conclude that ISCoffee - on the short term - will not manage to become a viable alternative to Northern-based private standards and certifications

Exploring the role of autonomous system behavior in lighting control

Modern distributed lighting systems require advanced control systems because of the large amount of light sources and manipulable parameters. In this position paper we explore the unknown dimensions that can be used to describe control from full-user to full-system control. We believe a hybrid between the two will be most desirable. Combined with explicit user interaction, autonomous system behavior will create intelligent systems, able to adapt to users and contexts. This provides interesting opportunities for improved user experience as well as functional added value, for instance in energy saving or easy commissioning of light infrastructure. Based on different types of interactions, different levels of interaction-initiative and different interaction layers, a useful mapping of such hybrid control can be made. In our lighting living labs, we have implemented different controls in order to evaluate them on the basis of user experience

Ab initio density-functional theory study of NHx dehydrogenation and reverse reactions on the Rh(1111) surface

The adsorption and dissociation of NHx fragments on the Rh(111) crystal surface have been studied using first-principles density-functional calculations. The stability and configurations of NHx species have been investigated and characterized using frequency analysis. The highest adsorption energies have been calculated for NH and N. Several paths of NHx (x=1–3) dehydrogenation and hydrogenation have been taken into account. The transition states have been determined and in detail analyzed. The activation barriers and thermodynamic and kinetic data have been calculated for all the elementary steps. The calculations have shown that the elementary reactions have significant barriers, between 0.7 and 1.1 eV. The transition states are regarded neither early nor late with respect to the distance in hyperspace between initial and final states. The NH3 dehydrogenation has been determined as the rate limiting step. For this elementary process there has been estimated a large contribution of the zero point energy to the activation barrier and a significant entropy activation