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991.
S. Tsroya B. Dolgin O. Pelled S. Cohen S. Mordechai U. German 《Journal of Radioanalytical and Nuclear Chemistry》2018,317(3):1211-1221
At nuclear installations a large number of samples is used to control operational tasks and health physics parameters. A fast screening process can be applied to provide immediate indication on possible contamination, and liquid scintillation counting (LSC) is the preferred method. Many LSC systems, which do not perform pulse shape analysis, are still in use. A screening procedure for these systems is presented based on three windows analysis. It may greatly reduce work and time, compared to using a proportional counter system, besides providing more accurate results. 相似文献
992.
David Cohen Takayasu Matsuo Xavier Raynaud 《Journal of Nonlinear Mathematical Physics》2014,21(3):442-453
A new multi-symplectic formulation of the two-component Camassa-Holm equation (2CH) is presented, and the associated local conservation laws are shown to correspond to certain well-known Hamiltonian functionals. A multi-symplectic discretisation based on this new formulation is exemplified by means of the Euler box scheme. Furthermore, this scheme preserves exactly two discrete versions of the Casimir functions of 2CH. Numerical experiments show that the proposed numerical scheme has good conservation properties. 相似文献
993.
994.
Reactions of the hydroxyl radical, OH, with several organic species of interest in combustion chemistry have been studied near 1200 K and 1 atm in shock tube experiments in which UV absorption was used to monitor the OH concentration. Rate coefficients were measured for the reactions of OH with 2,3-dimethylbutane, isooctane, neooctane, ethylene, propylene, acetylene, formaldehyde, methanol, and ethanol. The values were found to be (in units of 1012 cm3/mol-s): 21, 22, 18, 2.6, 9.6, 0.28, 12, 5.2, and 5.3. These measured values are compared with previous experimental results and, where appropriate, transition-state theory calculations. 相似文献
995.
Gabriela S. Del Buono Terry S. Cohen Peter J. Rossky 《Journal of Molecular Liquids》1994,60(1-3):221-236
Molecular dynamics simulations have been carried out for a Br− ion in aqueous solution in order to establish the effect of truncation of long-range interactions on the dynamical properties of the ion. Simulations using smooth truncation of the potential at different cutoff radii were carried out and compared to results using the Ewald summation method. It is shown that when small cutoffs are applied (i.e. Rc = 8Å), the calculations yield low ionic diffusion coefficients relative to experiment, as well as short-time dynamical behavior which is inconsistent with the Ewald calculations. As the cutoff is increased, the results approach both the Ewald and the experimental results. In contrast to the results with the truncated potential, the short-time dynamical behavior of the hydrated bromide ion obtained with the Ewald method can be described by simple Langevin dynamics. 相似文献
996.
The smectic order in thin and ultra thin films (150–600Å) of the chiral ferroelectric liquid crystal mixture ZLI-3654 is studied using the X-ray reflectivity technique. The spin cast films on various substrates (float glass, Si wafer, polymer coated glass, etc.) order spontaneously with smectic layering parallel to the substrate surface. A simple model which assumes a sinusoidal density modulation can describe well the experimental reflectivity profiles. The X-ray reflectivity provides a method to evaluate the phases of the structure factor. We demonstrate, for the first time, that is possible to extract the molecular tilt angle, , in ferroelectric liquid crystals from X-ray reflectivity measurements of ultra thin films. The temperature dependence of the tilt angle in the smectic C* phase are almost independent of the film thickness (down to 200 Å) and are similar to those in the bulk. 相似文献
997.
We calculate the effects of nuclear forces on the sticking in muon-catalyzed d-t fusion using theR-matrix method. The importance of the Bloch operator in this calculation is emphasized. We try to clarify some features in the formulation that seem to have caused confusion in the past. Some speculations are made regarding the remaining discrepancy of the calculated sticking with experimental values. 相似文献
998.
Eliahu Cohen Yair Avny Albert Zilkha 《Journal of polymer science. Part A, Polymer chemistry》1971,9(6):1469-1479
The anionic graft polymerization of propylene sulfide on cellulose membrane was studied. Alkali cellulosates were used to initiate graft polymerization, and graft polymers of high polypropylene sulfide content were obtained in good yields. The graft polymerization was accompanied by a certain extent of homopolymerization. The effects of reaction solvent, monomer concentration, cellulosate degree of substitution, and type of the alkali metal cellulosate on the graft polymer composition, yield, and on the molecular weight of the grafted side chains were investigated. 相似文献
999.
Orthonormal bases of compactly supported wavelet bases correspond to subband coding schemes with exact reconstruction in which the analysis and synthesis filters coincide. We show here that under fairly general conditions, exact reconstruction schemes with synthesis filters different from the analysis filters give rise to two dual Riesz bases of compactly supported wavelets. We give necessary and sufficient conditions for biorthogonality of the corresponding scaling functions, and we present a sufficient conditions for the decay of their Fourier transforms. We study the regularity of these biorthogonal bases. We provide several families of examples, all symmetric (corresponding to “linear phase” filters). In particular we can construct symmetric biorthogonal wavelet bases with arbitraily high preassigned regularity; we also show how to construct symmetric biorthogonal wavelet bases “close” to a (nonsymmetric) orthonormal basis. 相似文献
1000.
Presented are new analytic solutions to Einstein's field equations with properties normally associated with supernovas. These are the first analytic supernova models with pressure, temperature, and luminosity. These solutions are used to compare a radiative nonzero model (for which the pressure is continuous accross the outer boundary of the star) with a radiative zero model [(standard model) for which the pressure within the star is zero at the outer boundary]. 相似文献