High-throughput concept for tailoring switchable mirrors

The optical properties, the switching kinetics and the lifetime of hydrogen switchable mirrors based on Mg-Ni alloys are determined with particular regard to the composition of the optically active metal-hydride layer in combination with the thickness of the catalytic capping layer. For this, a high-throughput experiment is introduced. The switching kinetics and the reversibility of switchable mirrors are strongly thickness dependent, though the details hinge on the fine structure of the clustered capping layer. Therefore, the kinetics is correlated with the surface structures of Pd on Mg_yNi_1−y as investigated by scanning tunneling microscopy. The results are explained by the so-called strong metal-support interaction (SMSI) state, characterized by a complete encapsulation of the capping layer clusters by oxidized species originating from the support. The SMSI-effect is less important with increasing Pd-layer thickness, and is suppressed by a good wetting of the Pd-clusters on the optically active film. This explains the critical thickness for the catalyzed hydrogen uptake observed in many switchable mirror systems. Moreover, the degradation of the kinetics during cycling is found to depend on the Pd-layer thickness and on the gas environment. Only films, covered with at least 15 nm Pd, show small degradation caused by the SMSI-effect. The SMSI-effect is partly reversible: after changing the gas environment from hydrogen to oxygen, the oxide on the Pd-clusters can be partly removed.     

The six-vertex model eigenvectors as critical limit of the eight-vertex model bethe ansatz

The critical limit of the eight-vertex model eigenvectors obtained by means of the generalized Bethe Ansatz is shown to give the six-vertex eigenvectors as constructed in a previous paper by two of the authors. Furthermore, an explicit mapping is established between these eigenvectors and the usual Bethe Ansatz eigenvectors of the six-vertex model. This allows one to show that the indexv labeling the eight-vertex eigenstates becomes exactly the third component of the total spin in the critical limit.     

The Organization of Interaction Between Oil Refineries

The paper deals with the appropriate form of interaction between two refineries with different demand patterns. This problem can be formulated as finding a decentralized solution of linear programming problems linked by buying and selling activities. The complete problem is first solved for central values of product demands and costs and revenues. The structure of the basis then determines the organization of the interaction in terms of which unit sets quantities and which prices, or whether centralized decisions should be made. If, for expected values of product demand and costs, the structure of the basis is the same then the related organization of trading can be used for day-to-day transactions. For a well-known oil refinery model it is found that, for fairly large demand variations, decentralized interaction is effective, but that the structure of the basis changes easily with crude price variations, and that simulations did not converge for these variations.     

Mössbauer study of small amounts of iron in graphite,around the diamond-graphite pressure-temperature stability region

An exploratory Mössbauer spectroscopy study of the Fe-C system in the C rich region, prepared by high pressure-high temperature treatment near the graphite-diamond stability line, was made. The results obtained for the different processing conditions give no evidence of Fe intercalation in graphite. The presence of some water in the cell produced hydrated Fe complexes, which can explain the deleterious effect of water or hydrogen in the high pressure diamond synthesis.     

Moment problem for effect algebras

We present a solution to the moment problem for effect algebras, concerning mean values of all powers of an observable concentrated on the interval [0, 1] for states from a convex set. We give a solution for particular examples, e.g., for the set of all effect operators. We examine how this problem is related to a socalled E-property. Finally, we give a solution for observables studied in the operational approach to physical theories.     

Comparison of four quantification methods for the determination of PCB in transformer oils

The analysis of PCB in transformer oils has been achieved with three HRGC/ECD based methods, proposed by the International Electrotechnical Commission (IEC/TC 10), by the Comité Européen de Normalisation (CEN/TC 19/WG 22) and by the Deutsches Institut für Normung (DIN 51 527). The same clean-up, described in the CEN/TC 19/WG 22, has been used for all the samples, allowing a comparison of the quantification procedure only. The total chlorine content has also been determined with X-ray fluorescence. These different methods of quantification are compared and their application for legislative purposes is discussed.Dedicated to Professor Dr Dieter Klockow on the occasion of his 60th birthday     

Preconcentration of trace antimony in tap and sea water on activated alumina. Determination by graphite furnace atomic absorption spectrometry

Summary A method is described for antimony preconcentration based on retention on a column of activated alumina. Recovery is 80% when no pH-control and 4 mol/l HCl as eluent are used. The preconcentration factor is 400. The method was applied to the determination of antimony in spiked tap and sea water. The analytical performance of the method is discussed.     

Relational Control Structures

In this paper, we outline the use of relational control structures (Regel-Relative) to describe continuous-time linear systems and show how well known time-invariance from control theory can be defined by these algebraic structures. Furthermore, such important system properties as controllability and reachability are introduced to arbitrary (nonlinear, non-smooth, discontinuous) dynamical systems.