Guest Editorial: Special Issue on Global Hydrological Datasets for Local Water Management Applications

Water Resources Management -     

2-[–3H]deoxyglucose uptake patterns in rats exploring a six-arm radial tunnel maze: Differences between experienced and nonexperienced rats.

In an automated tunnel maze rats were allowed to explore either a 6-arm radial configuration ("experienced") or an alley maze configuration ("nonexperienced"). The activity of control rats was restricted to the center of the maze. After 8 daily sessions and a 5-day break, catheters were implanted into the jugular vein. Two days later, 2-deoxyglucose was administered before both experimental groups were exposed to the 6-arm radial configuration. Nonexperienced rats differed from experienced rats in terms of efficiency of exploration, but not in locomotor activity. Compared with experienced animals, nonexperienced rats showed an increase in 2-deoxyglucose uptake in prefrontal and cingulate cortices and in mediodorsal and laterodorsal thalamic nuclei. Exposure of rats to familiar and unfamiliar maze patterns resulted in different patterns of brain metabolic activity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A dynamic systems model of basic developmental mechanisms: Piaget, Vygotsky, and beyond.

A dynamic systems model is proposed on the basis of a general developmental mechanism adopted from the theories of J. Piaget and L. S. Vygotsky, more particularly a mechanism based on the concepts assimilation versus accommodation and actual development versus zone of proximal development. In the model, action and experience have a distributed effect on contents (skills, knowledge, rules, action patterns, etc.) ordered along an abstract developmental distance dimension. After a mathematical treatment of the model, an overview is given of empirical evidence on continuous and discontinuous change. The dynamic model is then applied to the classic Piagetian and the neo-Piagetian models, models of continuous and discontinuous domain-specific change, and to models of cognitive strategies, transitions, microdevelopment, and inter- and intraindividual variability. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

THE ETM METHOD FOR ASSESSING THE SIGNIFICANCE OF CRACK-LIKE DEFECTS IN ENGINEERING STRUCTURES

The Engineering Flaw Assessment Method, EFAM, is presently being developed at GKSS. It consists of several individual documents for determining material properties and the crack driving force. The present paper briefly describes the document EFAM ETM 97 which provides guidance for estimating the crack tip opening displacement (CTOD) and the J-integral as driving force parameters for homogeneous structures. The CTOD and J can be expressed as functions of applied force or applied strain.     

CHOOSE: Towards a metamodel for enterprise architecture in small and medium-sized enterprises

Enterprise architecture (EA) is a coherent whole of principles, methods, and models that are used in the design and realization of an enterprise’s organizational structure, business processes, information systems, and IT infrastructure. Recent research indicates the need for EA in small and medium-sized enterprises (SMEs), important drivers of the economy, as they struggle with problems related to a lack of structure and overview of their business. However, existing EA frameworks are perceived as too complex and, to date, none of the EA approaches are sufficiently adapted to the SME context. Therefore, this paper presents the CHOOSE metamodel for EA in SMEs that was developed and evaluated through action research in an SME and further refined and validated through case study research in five other SMEs. This metamodel is based on the essential dimensions of EA frameworks and is kept simple so that it may be applied in an SME context. The final CHOOSE metamodel includes only four essential concepts (i.e. goal, actor, operation, object), one for each most frequently used EA focus. As an example, an extract is included from the specific model that was created for the SME used in our action research. Finally, the CHOOSE metamodel is evaluated according to the dimensions essential in EA and the requirements for EA in an SME context.     

Cure kinetics, morphological and dynamic mechanical analysis of diglycidyl ether of bisphenol-A epoxy resin modified with hydroxyl terminated poly(ether ether ketone) containing pendent tertiary butyl groups

Hydroxyl terminated poly(ether ether ketone) based on tert-butyl hydroquinone (PEEKTOH) was used to modify a diglycidyl ether of bisphenol-A epoxy resin. A diamine, 4,4′-diaminodiphenylsulfone was used as the curing agent. Isothermal differential scanning calorimetric measurements of the blends were carried out at 180, 165 and 150 °C. The extent of reaction was found to decrease with the addition of PEEKTOH. The phenomenological model developed by Kamal was used for kinetic analysis of curing reaction. The curing reaction followed autocatalytic mechanism regardless of the presence and amount of oligomer present in the epoxy resin. The experimental and theoretical reaction rates were in good agreement during the initial stages of the reaction. The experimental values were lower than theoretical rate during the final stages of reaction due to increase in the viscosity of the system. A semiemperical model was used to explain diffusion control during final stages of reaction. The cured blends exhibited two phase morphology at all the curing temperatures. A uniform particle size distribution was observed at all compositions. The domain size decreased slightly with increase in oligomer content and with decrease in curing temperature. Finally, the viscoelastic properties were analysed using dynamic mechanical thermal analysis. Two T_gs corresponding to epoxy rich and thermoplastic rich phases were evident from the dynamic mechanical spectrum.     

PROBA-V mission for global vegetation monitoring: standard products and image quality

PROBA-V is a new global vegetation monitoring mission, to be launched in the second quarter of 2013. PROBA-V has been developed to show a consistent performance with SPOT-VEGETATION (SPOT-VGT) data, with similar spectral bands but with an improved spatial resolution of 1/3 km. The innovative mission concept has led to several key research topics related to image quality, which are discussed in this article. To support the existing VEGETATION user community, the data products for PROBA-V continue to provide daily top of canopy synthesis (S1-TOC) and 10 day synthesis products (S10-TOC). In addition, the new top of atmosphere daily synthesis (S1-TOA) products and a radiometrically/geometrically corrected (level 1C) product in raw resolution will also be provided for scientific users.     

Topology optimization of fail-safe structures using a simplified local damage model

Topology optimization of mechanical structures often leads to efficient designs which resemble statically determinate structures. These economical structures are especially vulnerable to local loss of stiffness due to material failure. This paper therefore addresses local failure of continuum structures in topology optimization in order to design fail-safe structures which remain operable in a damaged state.

A simplified model for local failure in continuum structures is adopted in the robust approach. The complex phenomenon of local failure is modeled by removal of material stiffness in patches with a fixed shape. The damage scenarios are taken into account by means of a minimax formulation of the optimization problem which minimizes the worst case performance.

The detrimental influence of local failure on the nominal design is demonstrated in two representative examples: a cantilever beam optimized for minimum compliance and a compliant mechanism. The robust approach is applied successfully in the design of fail-safe alternatives for the structures in these examples.

     

A directional data dissemination protocol for vehicular environments

This paper presents a simple and robust dissemination protocol that efficiently deals with data dissemination in both dense and sparse vehicular networks. Our goal is to address highway scenarios where vehicles equipped with sensors detect an event, e.g., a hazard and broadcast an event message to a specific direction of interest. In order to deal with broadcast communication under diverse network densities, we design a dissemination protocol in such a way that: (i) it prevents the so-called broadcast storm problem in dense networks by employing an optimized broadcast suppression technique; and (ii) it efficiently deals with disconnected networks by relying on the store-carry-forward communication model. The novelty of the protocol lies in its simplicity and robustness. Simplicity is achieved by only considering two states (i.e., cluster tail and non-tail) for vehicles. Furthermore, vehicles in both directions help disseminating messages in a seamlessly manner, without resorting to different operation modes for each direction. Robustness is achieved by assigning message delivery responsibility to multiple vehicles in sparse networks. Our simulation results show that our protocol achieves higher delivery ratio and higher robustness when compared with DV-CAST under diverse road scenarios.     

An interactive computer-based interface to support the discovery of individuals’ mental representations and preferences in decisions problems: An application to travel behavior

Growing emphasis is currently given in decision modeling on process data to capture behavioral mechanisms that ground decision-making processes. Nevertheless, advanced applications to elicit such data are still lacking. The Causal Network Elicitation Technique interview and card-game, both face-to-face interviews, are examples of a behavioral process method to obtain individuals’ decision-making by eliciting temporary mental representations of particular problems. However, to portray and model these representations into formal modeling approaches, such as Bayesian decision networks, an extensive set of parameters has to be gathered for each individual. Thus, data collection procedures for large sample groups can be costly and time consuming. This paper reports on the methodological conversion and enhancement of the existing elicitation methods into a computer-based interface that allows to not only uncover individuals’ mental representations but also to automate the generation of preference parameter elicitation questions. Results of such studies can be used to understand individuals’ constructs and beliefs with respect to decision alternatives, predict individuals’ decision behavior at a disaggregate level, and to assess behavioral changes due to differences in contexts and constraints.