Temperature Dependence of Energy Degradation in Organic Liquid Scintillators

Under high energy excitation, organic molecules are generally excited to electronic states above the first excited state. Since, at not too high solute concentrations, energy transfer in organic liquid scintillators occurs via the first excited electronic state, the efficiency of degradation to this state affects the overall light output. Experimental results for a number of systems, at temperatures from 20°C to 24°C are reported. It was found that the efficiency of degradation to the first excited state generally decreases with increasing temperature, with some variation among the solvents tested. It was found that; the greater the efficiency of degradation to the first excited state at 20°C, the less this efficiency varies with temperature.     

A short proof of the Oslo algorithm

A short proof of the Oslo algorithm is presented that uses a simple comparison of coefficients     

Nine years of research and development on advanced water electrolysis. A review of the research programme of the Commission of the European Communities

The development of advanced water electrolysis was one of the main tasks of the R & D programme on hydrogen funded, within its main R & D programme on Energy, by the Commission of the European Communities. Most of the work has been concentrated on the development of alkaline water electrolysis, as this process appears particularly promising. (Water electrolysis based on ‘acidic’ solid polymer electrolytes, developed during the last 10 years, seems to be a potentially attractive alternative technology, at least for electrolysers of smaller scale (up to 100kW). Even at this size, however, there is not yet evidence of any overall economic advantage over advanced alkaline cells.) The results of 9 years of R & D in this field are critically examined, by reviewing the improvements achieved on the components of the electrolytic cell as well as the overall modification of the cell design. The anode, cathode and diaphragm have been the components investigated, but also the constituent materials, the nature of the electrolyte and its operating conditions have been dealt with. Three main lines of advanced electrolyser development were identified in the course of these investigations. The corresponding charcteristics are:

1. low temperature (70°C to 90°C), low current density (i=0.1–0.3 A cm^?2);
2. moderate temperature (<120°C), high current density (i up to 1 A cm^?2), medium pressure (5–10 bars);
3. medium temperature (120–160°C), high current density (i=1–2 A cm^?2), moderately high pressure (30 bars).

In cell design, very compact cell units have been devised, in which a ‘zero gap’ configuration (anode and cathode are placed directly on the diaphragm) is generally adopted, resulting in very low internal cell resistance (about 0.2 Ω cm²). Potential energy savings of 20 to 30% can be anticipated for the advanced electrolysis. In addition to this work on advanced alkaline water electrolysis, some limited research efforts on high temperature (>1100 K) water vapour electrolysis have been made and are reported. The latter work has been concentrated on the production of thin-layer doped zirconia solid electrolytes (d=50μm), potentially leading to high performance cells. The economic implications of high-temperature vapour electrolysis, however, cannot be judged at the present status of development.     

On the transfer matrix of a neutral system: Characterizations of exponential stability in input—output terms

This paper investigates the stability of linear autonomous multivariable neutral systems from an input—output viewpoint. Several frequency-domain and input—output characterizations for exponential stability of neutral systems are given. We provide two examples which illustrate that the behaviour of neutral systems may be quite different from that of retarded systems. Moreover we give necessary and sufficient conditions for the transfer functions of a neutral system to belong to certain algebras of meromorphic functions introduced in this paper.     

Petri net modules in the transformation-based component framework

Component-based software engineering needs to be backed by thorough formal concepts and modeling techniques. This paper combines two concepts introduced independently by the two authors in previous papers. On one hand, the concept of Petri net modules introduced at IDPT 2002 in Padberg [J. Padberg, Petri net modules, Journal on Integrated Design and Process Technology 6 (4) (2002) 105–120], and on the other hand a generic component framework for system modeling introduced at FASE 2002 in Ehrig et al. [H. Ehrig, F. Orejas, B. Braatz, M. Klein, M. Piirainen, A generic component concept for system modeling, in: Proceedings of FASE ’02, Lecture Notes in Computer Science, vol. 2306, Springer, 2002]. First we develop a categorical formalization of the transformation based approach to components that is based on pushouts. This is the frame in which we show that Petri net modules can be considered as an instantiation of the generic component framework. This allows applying the transformation based semantics and compositionality result of the generic framework to Petri net modules. In addition to general Petri net modules we introduce Petri net modules preserving safety properties which can be considered as another instantiation of pushout based formalization of the generic framework.     

Adaptive QoS for Mobile Web Services through Cross-Layer Communication

Web services providers can use the WS-QoS framework to achieve QoS differentiation by integrating various aspects of distinct communication layers. An architecture based on the framework supports resource-constrained mobile devices, which will generate a large percentage of Web service requests in the future     

Attributed graph transformation with node type inheritance

The aim of this paper is to integrate typed attributed graph transformation with node type inheritance. Borrowing concepts from object oriented systems, the main idea is to enrich the attributed type graph with an inheritance relation and a set of abstract nodes. In this way, a node type inherits the attributes and edges of all its ancestors. Based on these concepts, it is possible to define abstract productions, containing abstract nodes. These productions are equivalent to a number of concrete productions, resulting from the substitution of the abstract node types by the node types in their inheritance clan. Therefore, productions become more compact and suitable for their use in combination with meta-modelling. The main results of this paper show that attributed graph transformation with node type inheritance is fully compatible with the existing concept of typed attributed graph transformation.