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1.
A simple pre-irradiation procedure for the separation of iodine from soil has been developed. A soil sample was heated in a quartz tube for 15 min at about 900 °C. The evaporated iodine was collected in activated charcoal, which was produced from phenol resin with low impurities. The charcoal, with sorbed iodine, was irradiated by neutrons and the128I produced was measured. A successful elimination of the background radioactivity due to the matrix elements was possible with this separation procedure. The detection limit by this method for soil samples was about 0.1 mg/kg (dry). The method has been applied to analyze selected soil samples. 相似文献
2.
Masakazu Muramatsu 《Mathematical Programming》1998,83(1-3):393-406
In this paper, we introduce an affine scaling algorithm for semidefinite programming (SDP), and give an example of a semidefinite
program such that the affine scaling algorithm converges to a non-optimal point. Both our program and its dual have interior
feasible solutions and unique optimal solutions which satisfy strict complementarity, and they are non-degenerate everywhere. 相似文献
3.
The subject of spectral distribution methods where one derives and applies the locally smoothed forms of observables in nuclei
is briefly reviewed. It is well understood that the local forms (with respect to energy) of the level density function, expectation
values and strength densities are Gaussian, linear (or ratio of Gaussians) and a bivariate Gaussian respectively. To accomodate
symmetries in the above forms, one has to deal with multivariate distributions in general; for example the angular-momentum
(J) decomposition leads to a bivariate Gaussian form for the level density. These results extend to indefinitely large spaces
by method of partitioning and they generate convolution forms. The origin of these remarkable spectral properties is discussed
and shell model examples are given to substantiate their applicability to nuclear systems. Spectral distribution theory is
a practical, usable theory because the smoothed forms are defined in terms of traces of low particle-rank operators, and the
trace information propagates. Finally we discuss the application of the spectral methods for a wide range of nuclear problems;
these include binding energies, orbit occupancies, electromagnetic andβ-decay sum rule quantities, analysis of operators, symmetry breaking, numerical level densities, and determination of bounds
on time-reversal non-invariant part of nucleon-nucleon interaction. 相似文献
4.
In this paper, we treat a domain optimization problem in which the boundary-value problem is a Neumann problem. In the case where the domain is in a three-dimensional Euclidean space, the first-order and the second-order necessary conditions which the optimal domain must satisfy are derived under a constraint which is the generalization of the requisite of constant volume.Portions of this paper were presented at the 13th IFIP Conference on System Modelling and Optimization, Tokyo, Japan, 1987. 相似文献
5.
Rao DP Sivakumar SV Mandal S Kota S Ramaprasad BS 《Journal of chromatography. A》2005,1069(1):141-151
The separation of propylene-propane mixture is an energy intensive operation commercially practiced using cryogenic distillation. The separation by pressure swing adsorption has been studied as an alternative. A fixed-bed pressure swing adsorption yields the heavy component as a pure product. The product recovery and the productivity are not high. In a moving-bed process, because of the counter-current solid-gas contact, the separation achieved is similar to that of the fractionation by distillation. Although the moving-bed operation offers the upper limit for the performance of a cyclic adsorptive process, due to mechanical complexities in the handling of solids the 'simulated' moving-bed is preferred. By moving the inlet and outlet ports of streams located along the length of the bed, a moving-bed process can be realized in a fixed bed. We describe here a 'moving-port' system which permits injection or withdrawal of the fluid along the axial direction in a fixed bed. A fixed bed embedded with the moving-port systems emulates a simulated moving-bed adsorber. The proposed adsorber can fractionate a binary gas mixture into two product streams with high purities. It is similar to the Sorbex process of UOP but does not have the eluent as an additional separating agent. A parametric study indicates that high purity products and a higher productivity by an order of magnitude can be achieved with simulated moving-beds compared to the fixed beds. 相似文献
6.
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8.
In order to assess the levels and behavior of129I (half-life: 1.6×107 y) and127I (stable) in the environment, we have developed analytical procedures involving neutron activation analysis (NAA). Environmental samples collected around Tokaimura, Ibaraki Prefecture, Japan, have been analyzed using this method. Ranges of129I and127I concentrations in surface soil were 0.9–180 mBq kg–1 and 1–60 mg kg–1, respectively. Higher129I concentrations were found in soil samples collected from coniferous forests, suggesting a contribution from tree canopies in the deposition of this nuclide. Most of the129I in soil, was found to be retained in the first 10 cm. The129I/127I ratios in wheat fields were lower than those in rice paddy fields.A soil sample collected by IAEA from an area contaminated by the Chemobyl accident was also determined. The129I concentration and the129I/127I ratio were 1.6 mBq kg–1 and 1.7×10–7, respectively. The129I level in this sample was higher than the values obtained in areas far from nuclear facilities in Japan. It was suggested that the analysis of129I in soils in the Chernobyl area may be useful in evaluating the131I levels at the time of the accident.Analyses of129I and127I by ICP-MS in water samples were also made. The analytical speed of this method was very high, i.e., 3 minutes for a sample. However, there is a sensitivity limitation for129I detection due to interference from129Xe with the129I peak. The detection limits for129I and127I in water samples were about 0.5 mBq ml–1 and 0.1 ng ml–1, respectively. 相似文献
9.
Y. Muramatsu Y. Ohmomo D. Christoffers 《Journal of Radioanalytical and Nuclear Chemistry》1984,82(2):353-361
The possibilities of reactor induced (n, p) reactions as a tool for neutron activation analysis of titanium in geological samples are discussed. The interference of calcium and scandium is experimentally evaluated. Results for Ti, Ca and Sc in GSP-1 and PCC-1 standard rocks are presented. On the basis of the experimental values, it is concluded that the47Ti(n, p)47Sc reaction is the most favourable for titanium determination. 相似文献
10.
Acetophenone photo-sensitized addition of indene to cyclic fluoro-olefins (1,2-dichlorohexafluorocyclopentene-1, 1,2-dichlorotetrafluorocyclobutene-1 and hexafluorocyclobutene) gave the corresponding cycloadducts in satisfactory yields. The cycloadducts obtained predominantly had exo configuration.Some reactions such as reduction, oxidation, dechlorination and halogenation, of the cycloadducts were also studied. 相似文献