Parameter Inequalities for Orthogonal Arrays with Mixed Levels

An important question in the construction of orthogonal arrays is what the minimal size of an array is when all other parameters are fixed. In this paper, we will provide a generalization of an inequality developed by Bierbrauer for symmetric orthogonal arrays. We will utilize his algebraic approach to provide an analogous inequality for orthogonal arrays having mixed levels and show that the bound obtained in this fashion is often sharper than Raos bounds. We will also provide a new proof of Raos inequalities for arbitrary orthogonal arrays with mixed levels based on the same method.     

Effects of a prepulse on laser-induced EUV radiation conversion efficiency

The influence of prepulses on the conversion efficiency (CE) of laser radiation into 13 nm extreme ultraviolet (EUV) radiation, resulting from lithium-like oxygen ions from O20 μm water droplets, was investigated. The laser pulse durations in the experiment ranged from 200 fs to 120 ps. Applying prepulses preceding the main pulse at various delays of up to 11 ns, it was shown that the CE increases differently for each measured pulse duration. The strongest dependence on the introduction of a prepulse was observed for 2 ps laser pulses with a 20 mJ laser pulse energy. The EUV CE was improved by a factor of 15 by the introduction of a prepulse. Calculations on the atomic physics of oxygen ions and simulations of the laser–plasma interaction revealed the influence of the prepulse on the EUV yield. Received: 25 October 2002 / Published online: 22 January 2003 RID="*" ID="*"Corresponding author. Fax: +49-3641/947-202, E-mail: duesterer@ioq.uni-jena.de     

Escape factors in spherically symmetric plasmas

In this paper we present explicit formulas for the escape factors of strong spectral lines in spherical-symmetric plasmas. The plasma does not necessarily have a homogeneous density. The calculations include two new elements: the first incorporates an accurate calculation of the angle-averaged areal density of ions from any internal point to the edge of the sphere. The second is the use of a saddle point method to carry out the integration over the line profile. Approximate expressions for the asymptotic behavior of the escape factor are given for Gaussian, Lorentzian and Holtsmarkian line shapes.     

Sequencing and scheduling for filling lines in dairy production

We consider an integrated sequencing and scheduling problem arising at filling lines in dairy industry. Even when a processing sequence is decided, still a scheduling problem has to be solved for the sequence. This incorporates typical side constraints as they occur also in other sequencing problems in practice. Previously, we proposed a framework for general sequencing and scheduling problems: A genetic algorithm is utilized for the sequencing, incorporating a problem specific algorithm for the fixed-sequence scheduling. In this paper, we investigate how this approach performs for filling lines. Based on insights into structural properties of the problem, we propose different scheduling algorithms. In cooperation with Sachsenmilch GmbH, the algorithm was implemented for their bottleneck filling line, and evaluated in an extensive computational study. For the real data from production, our algorithm computes almost optimal solutions. However, as a surprising result, our simple greedy algorithms outperform the more elaborate ones in many aspects, showing interesting directions for future research.     

Generation of Silicone Poly‐HIPEs with Controlled Pore Sizes via Reactive Emulsion Stabilization

Macrocellular silicone polymers are obtained after solidification of the continuous phase of a poly(dimethylsiloxane) emulsion, which contains poly(ethylene glycol) drops of sub‐millimetric dimensions. Coalescence of the liquid template emulsion is prohibited by a reactive blending approach. The relationship is investigated in detail between the interfacial properties and the emulsion stability, and micro‐ and millifluidic techniques are used to generate macrocellular polymers with controlled structural properties over a wider range of cell sizes (0.2–2 mm) and volume fractions of the continuous phase (0.1%–40%). This approach could easily be transferred to a wide range of polymeric systems.

     

Isolated and solvated thioxanthone: a photophysical study

Quantum chemical methods have been employed to study the photophysics of thioxanthone in vacuum and various solvents. Structurally, the solvation leads to a lengthening of the carbonyl bond, whereas the benzene skeleton is mostly unaffected. This is mirrored by the larger blue shift of the (n(O)π*) states as compared to the red shift which the (ππ*) states undergo. For a proper understanding of the radiative and radiationless processes occurring, the excitation energy profile along a linearly interpolated path has been determined in various cases. The interesting interplay of excited states thus revealed, has been investigated to qualitatively suggest the relaxation pathways available (or dominant) in the cases under study. Rates for these processes have also been computed wherever possible.     

A new approach to the diastereoselective synthesis of aldols:Introduction of the 6α-(1R-hydroxyethyl) side chain of the carbapenem and penem antibiotics

The 6 α-(1R-hydroxyethyl) side chain has been introduced via a stereocontrolled aldol reaction with a silyl ketone as a hindered acetaldehyde equivalent. The derived trans-S silyl carbinol undergoes a completely stereospecific rearrangement to the desired trans-R O-silyl ether. The two-step sequence may be done in one-pot in overall yields of 70–90%.