Set-valued maps for image segmentation

The goal of this paper is an analytical basis of a region growing method using set-valued maps. They are to provide an approach to image segmentation that does not use a priori conditions on the final segment. Seizing a suggestion of Demongeot and Leitner ([8]), we start with a compact subset of the grey-valued image, and the region growing method is based on the continuous deformation of sets for decreasing some error functional. Avoiding any further restrictions on these sets leads to describing the process as a set-valued map. The ansatz of the deforming sets utilizes reachable sets of differential inclusions that admit more than one velocity of propagation at each point. So set-valued maps underlie a mathematical segmentation problem posed and solved in the first part. Then we present a suggestion how to apply the analytical results to a very simple computer implementation. Received: 2 March 2000 / Accepted: 27 May 2001     

Properties of CsI(TI) — Renaissance of an old scintillation material

CsI(TI) is an interesting material for calorimeters in high energy physics. Properties of this material are reported.     

Theoretical fitting characteristics of typical soft contact lens designs

Purose

To calculate theoretical fitting success rates (SR) for a range of typical soft contact lens (SCL) designs using a mathematical model.

Structure of Na Species in Promoted CaO-Based Sorbents and Their Effect on the Rate and Extent of the CO2 Uptake

To advance CaO-based CO₂ sorbents it is crucial to understand how their structural parameters control the cyclic CO₂ uptake. Here, CaO-based sorbents with varying ratios of Na₂CO₃:CaCO₃ are synthesized via mechanochemical activation of a mixture of Na₂CO₃ and CaCO₃ to investigate the effect of sodium species on the structure, morphology, carbonation rate and cyclic CO₂ uptake of the CO₂ sorbents. The addition of Na₂CO₃ in the range of 0.1–0.2 mol% improves the CO₂ uptake by up to 80% after 10 cycles when compared to ball-milled bare CaCO₃, while for Na₂CO₃ loadings >0.3 mol% the cyclic CO₂ uptake decreases by more than 40%. Energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy, X-ray absorption spectroscopy (XAS), and ²³Na MAS NMR, reveal that in sorbents with Na₂CO₃ contents <0.3 mol% Na exists in highly distributed, noncrystalline [Na₂Ca(CO₃)₂] units. These species stabilize the surface area of the sorbent in pores of diameters >100 nm, and enhance the diffusion of CO₂ through CaCO₃. For Na₂CO₃ contents >0.3 mol%, the accelerated deactivation of the sorbents via sintering is related to the formation of crystalline Na₂Ca(CO₃)₂ and the high mobility of Na.     

Diffundierter Sauerstoff als dominierender flacher Akzeptor in p-Typ Kupferiodid-Dünnfilmen

The long-term stability of the optically transparent p-type semiconductor copper iodide is a current challenge. The electrical conductivity of CuI thin films depends critically on the environmental impact. Al₂O₃ cappings enhance the stability considerably. Systematic studies on Al₂O₃/CuI heterostructures in dependence of the N₂/O₂ growth pressure show the electrical conductivity of the CuI films being determined by the oxygen diffusion through Al₂O₃ und CuI. Oxygen seems to be a dominating acceptor in CuI. We traced the diffusion of atmospheric oxygen into CuI with ¹⁸O isotopes.     

A rotor lamination design for surface permanent magnet retention athigh speeds

A major problem in the design and manufacturing of surface mounted permanent magnet machines is reliably holding the permanent magnets in place at high speeds. This paper evaluates a unique rotor lamination design for a high pole number, permanent magnet alternator. This buried magnet design, which is capable of reliably holding the permanent magnets in place at high speeds, offers both easier and cheaper assembly when compared with the methods currently used in surface mounted permanent magnet machines. Finite element analysis is used to compare the buried magnet design with equivalent surface mounted designs and shows that the performance of the alternator is not significantly affected by the iron over the magnets. Experimental results from a prototype alternator further corroborate the FEA and show that the design is capable of operating at high speeds with no other means of magnet retention. In addition, an improvement in the buried magnet design which can reduce the lamination complexity is suggested and examined     

Flux-based active filter controller

This paper presents a synchronous frame flux-based control method for a parallel active filter application. The flux-based controller directly implements the inverter switchings in the synchronous reference frame by a hysteresis rule-based carrier-less pulse-width modulation (PWM) strategy to achieve high current bandwidth. This paper addresses the issues and impact on parallel active filtering requirements for utility interface of commonly used harmonic front-ends. The synchronous frame flux-based controller provides additional insights for harmonic current compensation requirements. Simulation results provide the validation of the flux-based active filter controller to meet IEEE Standard 519 recommended harmonic standards for large rated nonlinear loads under balanced and unbalanced supply conditions     

Alternative electro-chemically based processing routes for joining of plasma facing components

Tungsten is considered in fusion technology as functional and structural material in the area of blanket and divertor for future application in DEMO. The KIT design of a He-cooled divertor includes joints between W and W-alloys as well as of W with Eurofer-steel. The main challenges range from expansion mismatch problem for tungsten/steel joints over metallurgical reactions with brittle phase formation to crack stopping ability and excellent surface wetting. These requirements were only met partly and insufficiently in the past e.g. by direct Cu-casting of tungsten onto steel.Both, the joining needs and the observed failure scenarios of conventionally joined components initiated the development of improved joining technologies based on electro-chemical processing routes. As electrolytes aqueous and aprotic, water free, system are integrated into this development line. In the first step principle requirements are presented to guarantee a reproducible and adherent deposition of scales based on Ni and Cu acting as inter layers and filler, respectively, to generate a real metallurgical bonding as demonstrate by 1100 °C joining tests. The development field aprotic systems based on ionic liquids is discussed with respect to enable development of refractory metal based fillers with focus high temperature W–W brazing.     

Aerodynamic Part Feeding: Development of Aerodynamic Orienting Devices

Because of the pressure for continuous rationalisation, companies especially in industrialised countries, have to reduce their unit costs. A common way to fulfil this demand is to reduce labour costs by using fully automatic assembly systems. The assembly process itself has been optimised using many disciplines. Assembly has become more flexible and faster. This rapid improvement, however, cannot be observed in the area of part-feeding systems. In spite of the fact that part feeding is a key technology for high efficiency in fully automated assembly systems, the devices which provide the assembly processes with small parts have not generally improved in the last decades. Hence, innovative feeding technologies based on aerodynamic effects are being developed at the Institute of Production Systems. In this paper we focus on the orientation function of the feeding process.