Workstage repair policies for sequential manufacturing systems

Dynamic stage repair policies where the stage repair probabilities are determined by the number of items in the buffer are examined through a model of a manufacturing system with two unreliable workstages connected by a minimal intermediate storage buffer. Definitions for workstage availability and line balance are extended for sequential manufacturing systems with dynamic repair policies. A measure for stage repair inputs and a general form of dynamic stage repair policies are presented. The steady-state probabilities of the resultant state-inhomogeneous Markov chain are computed by an efficient solution procedure. Insights obtained from extensive numerical studies are illustrated and discussed.     

Zur komplexchemie von 4-zentren-π-systemen : XII. Glyoxaldiiminkomplexe: 1H-nmr-spektren und long range-kopplungen

Glyoxaldiimines (I) RN=CHCH=NR show in the NMR a downfield shift of glyoxalic protons (H_gly) when complexed to

(II: M = Mo, W), but increasing high field shifts when going to

(III) and

complexes (IV). In the tungsten complexes II H_glyW coupling satellites are resolved (J(WH) ≈4–6 Hz); in the phosphine compounds III, IV long range PH_gly coupling is clearly visible. Mechanisms of spinspin interaction are briefly discussed in connection with the EPR results on monoanionic radicals of II–IV.     

Structures of two novel monoterpene alkaloid glucosides from Lonicera Xylosteum L.

The structures of loxylostosidine A and B, two new sulfoxide - containing monoterpene alkaloid glucosides, are described.     

Zur komplexchemie von 4-zentren-π-systemen : VIII. ESR-untersuchungen an heterobutadien-chelaten. I. Kalium-(diazabutadien-tetracarbonyl-metallate)

Glyoxal- and diacetyl-bis(imine)metal tetracarbonyls (RNCR′CR′NR)M(CO)₄ (M = Cr, Mo, W) are reduced with potassium in DME to give paramagnetic mono-anions. Their high-resolutior, ESR spectra show the hyperfine splittings of the magnetically active ligand atoms as well as the satellites of the metal isotopes ⁵³Cr,^95,97Mo and ¹⁸³W. The coupling constants are discussed with respect to π-bonding mechanisms.     

Über projektive Moduln und Endlichkeitshindernisse bei Transformationsgruppen

We study projective modules in the category of functors from homogeneous spaces into abelian groups. Such functors have been considered by Bredon [1]. We show that protective functors are determined by a set of ordinary projective modules over suitable group rings. The general notions are applied to give a quick proof for the product formula of the finiteness obstruction for transformation groups. These finiteness obstructions are straightforward extensions of the Swan-Wall obstructions (see e. g. Quinn [7]). They are important in the study of homotopy representations (tom Dieck — Petrie [3], [4]). This work is also related to Rothenberg [8].     

Modellkomplexe mit Hydrazonchelaten von (S)- und (R)-1-Amino-2-methoxymethylpyrrolidin („SAMP”︁ und „RAMP”︁) und Dimethylhydrazin - Struktur des Pyridinaldehyd-RAMP-hydrazon-tetracarbonyl-molybdäns

Model Complexes with Hydrazone Chelates of (S)- and (R)-1-Amino-2-methoxymethylpyrrolidine (?SAMP”? and ?RAMP”?) and Dimethylhydrazine — Structure of (Pyridine-2-aldehyde-RAMP-hydrazone)tetracarbonyl-molybdenum The hydrazones of glyoxal, biacetyl, pyridine-2-aldehyde and 2-acetylpyridine with N,N-dimethylhydrazine and (R)- and (S)-1-amino-2-methoxymethylpyrrolidine are synthesized and reacted with hexacarbonylmolybdenum to give the chelate hydrazone tetracarbonylmolybdenum complexes. In contrast to the pure electronic effect of methyl groups complexes derived from biacetyl (relativ to glyoxal) or from acetylpyridine (rel to the aldehyde) show a long-wavelength shift of the characteristic MLCT absorption band in their electric spectra, indicativ of a dominant steric effect. A single crystal x-ray diffraction study on (pyridine-2-aldehyde-RAMP-hydrazone)tetracarbonylmolybdenum 12 proves the conjugative interaction of the sp²-hybridized amino nitrogen with the chelate π-system. Orthorhombic 12 crystallizes in space group P2₁2₁2 with 4 molecules in the unit cell: a = 14.689(4), b = 15.699(1) and c = 7.866(6) Å, V = 1814 ų. Complete ¹H and ¹³C nmr parameter are given for the ligands and the complexes.     

Rhodium-Katalysierte Isomerisierungen von 2-Methylidenglutarsäureestern zu Methylglutaconsäureestern

The Rhodium(III)-catalyzed thermal isomerization of 2-methylidenglutaric acid esters affords predominantly mixtures of cis/trans-2-methylglutaconic acid esters ( 2, 3 ) which upon slow distillation isomerize completely into the cis-esters ( 2 ). Saponification of 2 yields trans-2-methylglutaconic acid ( 5 ). Attempts to prepare the acid chloride of 5 produces 6-chloro-5-methylpyrone-2 ( 9 ) or 6-chloro-3-methylpyrone-2 ( 10 ) which react with anilines to N-substituted derivatives of trans-4-methylglutaconic acid amides ( 11 ). The thermal isomerizations of the respective esters are discussed in terms of 1,5-hydrogen shifts in their ester enol structures.     

Elektronenreiche übergangsmetallkomplexe : II. Nitril-phosphan-molybdändicarbonyle: Farbe und solvatochromie

Complexes of aromatic or α,β-unsaturated nitriles YCN of the type (YCN)₂(PR₃)₂Mo(CO)₂ and (YCN)(PR₃)₃Mo(CO)₂ are new chromophores. Their intense electronic absorption band in the visible spectrum is strongly influenced by substituents and solvent polarity. Acceptor properties of nitriles are discussed on the basis of CNDO-calculations. CT-character and solvato-chromism can be interpreted in terms of the back-bonding ability of the nitriles in electron-rich metal complexes.