On triangular norm based axiomatic extensions of the weak nilpotent minimum logic

In this paper we carry out an algebraic investigation of the weak nilpotent minimum logic (WNM) and its t‐norm based axiomatic extensions. We consider the algebraic counterpart of WNM, the variety of WNM‐algebras (?????) and prove that it is locally finite, so all its subvarieties are generated by finite chains. We give criteria to compare varieties generated by finite families of WNM‐chains, in particular varieties generated by standard WNM‐chains, or equivalently t‐norm based axiomatic extensions of WNM, and we study their standard completeness properties. We also characterize the generic WNM‐chains, i. e. those that generate the variety ?????, and we give finite axiomatizations for some t‐norm based extensions of WNM. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis,Characterization, and Energetic Properties of Salts of the 1-Cyanomethyl-1,1-dimethylhydrazinium Cation

1,1-Dimethylhydrazine can be readily alkylated with bromoacetonitrile to form 1-cyanomethyl-1,1-dimethylhydrazinium bromide ([(CH₃)₂N(CH₂CN)NH₂]Br, 1 ). The metathesis reaction of compound 1 led to the formation of a new family of energetic salts based on the [(CH₃)₂N(CH₂CN)NH₂]⁺ cation and nitrate ( 2 ), perchlorate ( 3 ), azide ( 4 ), 5-aminotetrazolate ([H₂N-CN₄]⁻, 5 ), 5,5′-azobistetrazolate ([N₄C-NN-CN₄]²⁻, 7 ), and picrate ( 8 ) anions. The new materials were characterized by elemental analysis, mass spectrometry, and (multinuclear) NMR and vibrational (infrared and Raman) spectroscopies. Additionally, the molecular structure of the [(CH₃)₂N(CH₂CN)NH₂]⁺ cation in compounds 1 , 3 , and 8 and that of sodium 5,5′-azobistetrazolate octahydrate (NaZT⋅8 H₂O) were solved by X-ray diffraction techniques. The hydrogen-bonding networks found in the structure of salts 1 , 3 , 8 , and NaZT⋅8 H₂O are described using graph-set analysis. The melting and decomposition points of the new compounds were determined by differential scanning calorimetry, and insight into their sensitivity towards impact, friction, and electrostatics was gained by submitting the materials to standard tests. Furthermore, we estimated some performance parameters of interest and predicted the decomposition gases formed upon decomposition of salts 2 , 3 , 4 , 5 , 6 , 7 , 8 and of mixtures with an oxidizer. The interesting thermal, sensitivity, and performance properties of some of the compounds described in this work make them attractive towards a prospective energetic application.     

Optimal complexity of secret sharing schemes with four minimal qualified subsets

The complexity of a secret sharing scheme is defined as the ratio between the maximum length of the shares and the length of the secret. This paper deals with the open problem of optimizing this parameter for secret sharing schemes with general access structures. Specifically, our objective is to determine the optimal complexity of the access structures with exactly four minimal qualified subsets. Lower bounds on the optimal complexity are obtained by using the known polymatroid technique in combination with linear programming. Upper bounds are derived from decomposition constructions of linear secret sharing schemes. In this way, the exact value of the optimal complexity is determined for several access structures in that family. For the other ones, we present the best known lower and upper bounds.     

Phase mask selection in wavefront coding systems: A design approach

A method for optimizing the strength of a parametric phase mask for a wavefront coding imaging system is presented. The method is based on an optimization process that minimizes a proposed merit function. The goal is to achieve modulation transfer function invariance while quantitatively maintaining final image fidelity. A parametric filter that copes with the noise present in the captured images is used to obtain the final images, and this filter is optimized. The whole process results in optimum phase mask strength and optimal parameters for the restoration filter. The results for a particular optical system are presented and tested experimentally in the laboratory. The experimental results show good agreement with the simulations, indicating that the procedure is useful.     

Uranyl-peroxide nanocapsules: electronic structure and cation complexation in [(UO2)20(μ-O2)30]20-

The pentagonal K(10)[(UO(2))(5)(μ-O(2))(5)(C(2)O(4))(5)] species have been identified as the building blocks of uranyl-peroxide nanocapsules. The computed complexation energies of different alkali cations (Li(+), Na(+), K(+), Rb(+), and Cs(+)) with [(UO(2))(5)(μ-O(2))(5)(O(2))(5)](10-) and [(UO(2))(20)(μ-O(2))(30)](20-) species suggest a strong cation templating effect. In the studied species, the largest complexation energy occurs for the experimentally used alkali cations (Na(+) and K(+)).     

Synthesis,Characterization, and Energetic Properties of Nitroso Compounds

Sodium and potassium methyl(nitroso)amide (M[CH₃N₂O], M = Na ( 1 ), K ( 2 )) were prepared by the reaction of monomethylhydrazine with iso‐pentyl nitrite or n‐butyl nitrite and a suitable metal ethoxide (M[CH₃CH₂O], M = Na, K) in an ethanol‐ether mixture. The reaction of monomethylhydrazine with a small excess of iso‐pentyl nitrite or n‐butyl nitrite and in the absence of a metal ethoxide led to the formation of N‐nitroso‐N‐methylhydrazine (CH₃(NO)N–NH₂, ( 3 )). Alternatively, compound 3 was prepared by the amination reaction of 1 or 2 using the sodium salt of HOSA in ethanol solution. Compounds 1–3 were characterized using elemental analysis, differential scanning calorimetry, mass spectrometry, vibrational (infrared and Raman) and UV spectroscopy and multinuclear (¹H, ¹³C and ¹⁵N) NMR spectroscopy. For compounds 1–3 , several physical and chemical properties of interest and sensitivity data were measured and for compound 3 thermodynamic and explosive properties are also given. Additionally, the solid‐state structure of compound 3 was determined by single‐crystal X‐ray analysis and the structures of the cis‐ and trans‐[CH₃N₂O]^– anions and that of 3 were optimized using DFT calculations and used to calculate the NBO charges.