Walter A. Frank

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In this paper we describe a noise reduction preprocessing algorithm for the adaptive multirate (AMR) speech codec of the GSM system. The algorithm is based on spectral weighting and explicitly takes into account the properties of the human auditory system. The weighting rule results in the smallest possible speech distortion under the constraint that the(More)
The asymmetric unit of the title salt, [H3N(CH2)6NH3][(HO)O2P(CH2)6PO2(OH)], consists of one half of a hexane-1,6-diaminium dication and one half of a hexane-1,6-diyl bis-(hydrogen phospho-nate) dianion. Both are located around different centres of inversion (Wyckoff sites: 2a and 2d) of the space group P21/c. The shape of the hexane-1,6-diaminium cation is(More)
The asymmetric unit of the title mol-ecular salt, [C5H7N2+][(HO)2OP(CH2)9PO2(OH)-], consists of one 4-amino-pyridinium cation and one hydrogen (9-phos-phono-non-yl)phospho-nate anion, both in general positions. As expected, the 4-amino-pyridinium moieties are protonated exclusively at their endocyclic nitro-gen atom due to a mesomeric stabilization by the(More)
The title compound, [Al(H(2)O)(6)](CH(3)SO(3))(3) (common name: aluminium methane-sulfonate hexa-hydrate), was crystallized from an aqueous solution prepared by the precipitation reaction of aluminium sulfate and barium methane-sulfonate. Its crystal structure is the first of the boron group methane-sulfonates to be determined. The characteristic building(More)
Racemic boronate-imine and boronate-amine complexes 8 and 10, both featuring a stereogenic boron atom were synthesized from 2-amino-1,1-diphenylethanol (5) and characterized by crystal structure analyses. Proof of enantiomerism at the boron center for the novel boronate-amine complex 10 was established by separation of the enantiomers. Racemization barriers(More)
Single crystals of the title compound, (imidazolium-2-yl)phenyl-phosphinate monohydrate, C(9)H(9)N(2)O(2)·H(2)O, were ob-tained from methanol/water after deprotection and oxidation of bis-(1-diethoxy-methyl-imidazol-2-yl)phenyl-phosphane. In the structure, several N-H⋯O and P-O⋯H-O hydrogen bonds are found. π-π inter-actions between the protonated(More)
A whole family of annelated 4H-thiopyran-4-ones as the core structural unit was readily synthesized in good yields by a microwave-assisted coupling-addition-S(N)Ar (CASNAR) sequence starting from readily available (het)aroyl chlorides, alkynes and sodium sulfide nonahydrate in a consecutive one-pot three-component reaction. All representatives display a(More)