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141.
142.
An improved typology of cutting and packing problems 总被引:1,自引:0,他引:1
The number of publications in the area of Cutting and Packing (C&P) has increased considerably over the last two decades. The typology of C&P problems introduced by Dyckhoff [Dyckhoff, H., 1990. A typology of cutting and packing problems. European Journal of Operational Research 44, 145–159] initially provided an excellent instrument for the organisation and categorisation of existing and new literature. However, over the years also some deficiencies of this typology became evident, which created problems in dealing with recent developments and prevented it from being accepted more generally. In this paper, the authors present an improved typology, which is partially based on Dyckhoff’s original ideas, but introduces new categorisation criteria, which define problem categories different from those of Dyckhoff. Furthermore, a new, consistent system of names is suggested for these problem categories. Finally, the practicability of the new scheme is demonstrated by using it as a basis for a categorisation of the C&P literature from the years between 1995 and 2004. 相似文献
143.
H. Deutsch K. Becker P. Defrance M. Probst J. Limtrakul T. D. Märk 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(3):489-493
New measurements of the cross-section for electron impact ionization of the
molecular ion C2H2+ have been carried out recently. These
data differ significantly from earlier data, because cross-sections
corresponding to all the possible dissociative ionization processes were
determined. The new data in conjunction with the significant discrepancies
between the earlier data and the results of various calculations, which
disagreed among themselves by a factor of 3, motivated a renewed attempt to
apply the semi-classical Deutsch-M?rk (DM) formalism to the calculation
of the absolute electron-impact ionization cross-section of this molecular
ion. A quantum chemical molecular orbital population analysis for both the
neutral molecule and the ion revealed that in the case of
C2H2+ the singly occupied molecular orbital (i.e. the
“missing” electron) is highly localized near the site of a C atom in the
molecule. This information is explicitly incorporated in our formalism. The
results obtained by taking the ionic character directly into account are in
excellent agreement with the recent experimental data. 相似文献
144.
145.
146.
147.
Heike Mildenberger 《Archive for Mathematical Logic》1992,31(6):445-455
Summary The local homogeneity property is defined as in [Mak]. We show thatL
(Q1) and some related logics do not have the local homogeneity property, whereas cofinality logicL
(Q
cf) has the homogeneity property. Both proofs use forcing and absoluteness arguments. 相似文献
148.
149.
Fliegl H Köhn A Hättig C Ahlrichs R 《Journal of the American Chemical Society》2003,125(32):9821-9827
We report accurate geometries and harmonic force fields for trans- and cis-azobenzene determined by second-order M?ller-Plesset perturbation theory. For the trans isomer, the planar structure with C(2h) symmetry, found in a recent gas electron diffraction experiment, is verified. The calculated vibrational spectra are compared with experimental data and density functional calculations. Important vibrational frequencies are localized and discussed. For both isomers, we report UV spectra calculated using the second-order approximate coupled-cluster singles-and-doubles model CC2 with accurate basis sets. Vertical excitation energies and oscillator strengths have been determined for the lowest singlet n(pi)* and (pi)(pi)* transitions. The results are compared with the available experimental data and second-order polarization propagator (SOPPA) and density functional (DFT) calculations. For both isomers, the CC2 results for the excitation energies into the S(1) and S(2) states agree within 0.1 eV with experimental gas-phase measurements. 相似文献
150.