Ueber die Bestimmung der St?rke in Cerealien, Kartoffeln und in der Handelsst?rke

Ohne Zusammenfassung     

Self‐diffusion coefficients obtained from proton‐decoupled carbon‐13 spectra for analyzing a mixture of terpenes

In the limit of sufficient sensitivity, natural abundance ¹³C offers a much better spectral resolution than proton NMR. This is due to an important chemical shift range and to proton‐decoupling conditions that yield one peak per carbon with practically no overlap. However, pulsed gradient spin echo experiments, which lead to the diffusion coefficient associated with each peak, have scarcely been employed. In this article, we present and compare different ways to access this quantity and we have effectively verified that, without any precaution, diffusion coefficients cannot be properly determined from standard procedures. The cause of such a failure is decoupling during the gradient pulses. We have used a very simple remedy that proved to be very successful on a model mixture of three monoterpenes and that appears as being of general applicability. Copyright © 2009 John Wiley & Sons, Ltd.     

All-optical wavelength converters for optical switching applications

We present the latest results about all-optical wavelength conversion obtained within the European Union—funded RACE ATMOS project. In particular, solutions based on carrier depletion in Distributed Brag Reflector lasers have reached penalty-free polarization-insensitive operation at up to 2.5 Gbit/s, while solutions based on Semiconductor Optical Amplifiers (SOAS) under cross-gain modulation have been demonstrated at more than 20 Gbit/s. The study of cross-phase modulation in SOAs has also been performed, leading to the monolithic integration of SOAs within an interferometer, according to structures proposed by the project. Penalty-free operation at up to 10 Gbit/s as well as signal reshaping have been obtained with such devices. Besides the study of components, wavelength converters have been used in several demonstrators assessing their maturity and compatibility with photonic-switching applications.     

Digital image correlation and biaxial test on composite material for anisotropic damage law identification

The purpose of the work is to extend the use of non-conventional tests and full field measurements to the identification of an anisotropic damage law. A Digital Image Correlation technique based on a finite element discretization is used to extract planar displacement fields. The reconditioned Equilibrium Gap Method is then used to retrieve a damage law that accounts for shear softening, a specific form suited to the present application. The identification is shown to reduce to a linear system. The example of a biaxial shear test performed on a cruciform specimen is considered. The approach is first qualified by using displacement fields resulting from a non-linear computation with a known damage law. A good agreement is observed between the prescribed and identified laws for distinct parameter settings, even when significant noise is added to the displacement fields. The reconstructed displacement fields coincide perfectly with the measurements. The complete scheme is finally tested considering images taken during an experiment performed on a carbon/carbon composite. The identified damage pattern and the corresponding damage values are similar to post-processed maps using classically identified parameters. The reconstructed displacement field accounts for 95% of the fluctuations observed in the measurements.     

Generally covariant quantization and the Dirac field

Canonical Hamiltonian field theory in curved spacetime is formulated in a manifestly covariant way. Second quantization is achieved invoking a correspondence principle between the Poisson bracket of classical fields and the commutator of the corresponding quantum operators. The Dirac theory is investigated and it is shown that, in contrast to the case of bosonic fields, in curved spacetime, the field momentum does not coincide with the generators of spacetime translations. The reason is traced back to the presence of second class constraints occurring in Dirac theory. Further, it is shown that the modification of the Dirac Lagrangian by a surface term leads to a momentum transfer between the Dirac field and the gravitational background field, resulting in a theory that is free of constraints, but not manifestly hermitian.     

Recovered efficiency of filter control in dispersion-managed solitons for optical regeneration applications: analysis and experimental validation

We demonstrate numerically that local conversion of dispersion-managed return-to-zero pulses into nonlinear Schr?dinger solitons fully restores optical filtering control for energy stabilization, thus permitting the association of optical regeneration with dispersion-managed propagation. Experimental validation is achieved by means of 40-Gbit/s regenerated dispersion-managed loop transmission over 10,000 km.     

k-Best constrained bases of a matroid

We propose a method for finding a set ofk-best bases of an arbitrary matroid where the bases are required to satisfy additional partitionlike constraints. An application of this problem is discussed.Research partly supported by Sonderforschungsbereich 303 der Deutschen Forschungsgemeinschaft and by the Austrian Science Foundation, Project P6004.     

Experimental and modeling study of the oxidation of 1‐pentene at high temperature

Ignition delay times of 1‐pentene–oxygen–argon mixtures have been measured behind shock wave, the onset of ignition being detected by OH radical emission. Mixtures contained 1 or 2% of hydrocarbon for equivalence ratios ranging from 0.5 to 2. Reflected shock waves allowed temperatures from 1130 to 1620 K and pressures from 7.3 to 9.5 atm to be obtained. A detailed mechanism of combustion of 1‐pentene has been automatically generated using EXGAS software. This mechanism has been validated by comparing the results of the simulations to the experimental ignition delay times. The main reaction pathways have been derived from flow rate and sensitivity analyses at different temperatures. Comparisons with 1‐butene and 1‐hexene in the same conditions show that 1‐pentene has a higher reactivity which seems to be due to its decomposition to give ethyl radicals, which rapidly yields very reactive hydrogen atoms, while the decomposition of 1‐butene and 1‐hexene leads to less reactive methyl radicals. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 451–463, 2005     

Ground state in FeS

From a Mössbauer study of oriented single crystals of Fe_0.996S and Fe_0.93S at 615 K (above the Néel transition $\text{T}{}_{\mathrm{N}}\text{\$}\text{?}\text{598}\text{K}$) the sign of the quadrupole splitting is determined to be negative thereby indicating the ground state is ${}^5\text{A}{}_1$.